THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 

GIFT  OF 

K.   L.  IIASSER 


STEAM  TURBINES 


Coal  Age  •»  Electric  Railway  Journal 
Electrical  \\forld  ^  Engineering  News-Record 
American  Machinist  v  jhe  Contractor 
Engineering 8 Mining  Journal  ^  Power 
Metallurgical  6  Chemical  Engineering 
Electrical  Merchandising 


THE    POWER    HANDBOOKS 

STEAM    TURBINES 

A  BOOK  OF  INSTRUCTION 

FOR  THE  ADJUSTMENT  AND   OPERATION  OF 

THE   PRINCIPAL   TYPES  OF  THIS 

CLASS  OF  PRIME  MOVERS 


COMPILED  AND  WRITTEN 
BY 

HUBERT    E.  COLLINS 


FIRST  EDITION 
THIRD  IMPRESSION 


McGRAW-HELL  BOOK  COMPANY,  INC. 
239  WEST  39TH  STREET.     NEW  YORK 


LONDON:  HILL  PUBLISHING  CO.,  LTD. 
6   &   8  BOTJVBRIE  ST.,   K.    C. 

1910 


Copyright,  1909,  BY  THE  HILL  PUBLISHING  COMPANY 


All  rights  reserved 


Engineering 
Library 

TJ 


CONTENTS 

CHAP.  PAGE 

I    CURTIS  STEAM  TURBINE  IN  PRACTICE i 

II    SETTING  THE  VALVES  OF  THE  CURTIS  TURBINE  .     .  31 

III  ALLIS-CHALMERS  STEAM  TURBINE 41 

IV  WESTINGHOUSE-PARSONS  TURBINE 58 

V    PROPER  METHOD  OF  TESTING  A  STEAM  TURBINE     .  112 

VI    TESTING  A  STEAM  TURBINE 137 

VII    AUXILIARIES  FOR  STEAM  TURBINES 154 

VIII    TROUBLE  WITH  STEAM  TURBINE  AUXILIARIES     .     .  172 


733816 


INTRODUCTION 

This  issue  of  the  Power  Handbook  attempts  to 
give  a  compact  manual  for  the  engineer  who  feels  the 
need  of  acquainting  himself  with  steam  turbines.  To 
accomplish  this  within  the  limits  of  space  allowed,  it 
has  been  necessary  to  confine  the  work  to  the  descrip- 
tion of  a  few  standard  types,  prepared  with  the 
assistance  of  the  builders.  Following  this  the  practi- 
cal experience  of  successful  engineers,  gathered  from 
the  columns  of  Power,  is  given.  It  is  hoped  that  the 
book  will  prove  of  value  to  all  engineers  handling 
turbines,  whether  of  the  described  types  or  not. 

HUBERT  E.  COLLINS. 
NEW  YORK,  April,  1909. 


THE  CURTIS  STEAM  TURBINE  IN  PRACTICE1 

"Op  the  making  of  books  there  is  no  end."  This 
seems  especially  true  of  steam-turbine  books,  but  the 
book  which  really  appeals  to  the  operating  engineer, 
the  man  who  may  have  a  turbine  unloaded,  set  up, 
put  in  operation,  and  the  builders'  representative  out 
of  reach  before  the  man  who  is  to  operate  it  fully 
realizes  that  he  has  a  new  type  of  prime  mover  on 
his  hands,  with  which  he  has  little  or  no  acquaintance, 
has  not  been  written.  There  has  been  much  published, 
both  descriptive  and  theoretical,  about  the  turbine, 
but  so  far  as  the  writer  knows,  there  is  nothing  in 
print  that  tells  the  man  on  the  job  about  the  details 
of  the  turbine  in  plain  language,  and  how  to  handle 
these  details  when  they  need  handling.  The  oper- 
ating engineer  does  not  care  why  the  moving  buckets 
are  made  of  a  certain  curvature,  but  he  does  care 
about  the  distance  between  the  moving  bucket  and 
the  stationary  one,  and  he  wants  to  know  how  to 
measure  that  distance,  how  to  alter  the  clearance, 
if  necessary,  to  prevent  rubbing.  He  doesn't  care 
anything  about  the  area  of  the  step-bearing,  but  he 
does  want  to  know  the  way  to  get  at  the  bearing  to 
take  it  down  and  put  it  up  again,  etc. 

1  Contributed  to  Power  by  Fred  L.  Johnson. 


2  STEAM  TURBINES 

The  lack  of  literature  along  this  line  is  the  writer's 
apology  for  what  follows.  The  Curtis  1 5oo-kilowatt 
steam  turbine  will  be  taken  first  and  treated  "from 
the  ground  up." 

On  entering  a  turbine  plant  on  the  ground  floor,  the 
attention  is  at  once  attracted  by  a  multiplicity  of 
pumps,  accumulators  and  piping.  These  are  called 
"auxiliaries"  and  will  be  passed  for  the  present  to 
be  taken  up  later,  for  though  of  standard  types  their 
use  is  comparatively  new  in  power-plant  practice,  and 
the  engineer  will  find  that  more  interruptions  of  ser- 
vice will  come  from  the  auxiliaries  than  from  the 
turbine  itself. 

BUILDERS'   FOUNDATION   PLANS   INCOMPLETE 

It  is  impractical  for  the  manufacturers  to  make 
complete  foundation  drawings,  as  they  are  not  familiar 
with  the  lay-out  of  pipes  and  the  relative  position  of 
other  apparatus  in  the  station.  All  that  the  manu- 
facturers' drawing  is  intended  to  do  is  to  show  the 
customer  where  it  will  be  necessary  for  him  to  locate 
his  foundation  bolts  and  opening  for  access  to  the 
step-bearing. 

Fig.  i  shows  the  builders'  foundation  drawing, 
with  the  addition  of  several  horizontal  and  radial  tubes 
introduced  to  give  passage  for  the  various  pipes  which 
must  go  to  the  middle  of  the  foundation.  Entering 
through  the  sides  of  the  masonry  they  do  not  block 
the  passage,  which  must  be  as  free  as  possible  when 
any  work  is  to  be  done  on  the  step-bearing,  or  lower 
guide-bearing.  Entering  the  passage  in  the  founda- 


CURTIS   STEAM   TURBINE   IN   PRACTICE  3 


4  STEAM  TURBINES 

tion,  a  large  screw  is  seen  passing  up  through  a  circular 
block  of  cast  iron  with  a  f-inch  pipe  passing  through 
it.  This  is  the  step-supporting  screw.  It  supports 
the  lower  half  of  the  step-bearing,  which  in  turn  sup- 
ports the  entire  revolving  part  of  the  machine.  It  is 
used  to  hold  the  wheels  at  a  proper  hight  in  the 
casing,  and  adjust  the  clearance  between  the  moving 
and  stationary  buckets.  The  large  block  which  with 
its  threaded  bronze  bushing  forms  the  nut  for  the 
screw  is  called  the  cover-plate,  and  is  held  to  the 
base  of  the  machine  by  eight  i^-inch  cap-screws.  On 
the  upper  side  are  two  dowel-pins  which  enter  the 
lower  step  and  keep  it  from  turning.  (See  Figs.  2 
and  3.) 

The  step-blocks  are  very  common-looking  chunks 
of  cast  iron,  as  will  be  seen  by  reference  to  Fig.  4. 
The  block  with  straight  sides  (the  lower  one  in  the 
illustration)  has  the  two  dowel  holes  to  match  the 
pins  spoken  of,  with  a  hole  through  the  center  threaded 
for  f -inch  pipe.  The  step-lubricant  is  forced  up  through 
this  hole  and  out  between  the  raised  edges  in  a  film, 
floating  the  rotating  parts  of  the  machine  on  a  friction- 
less  disk  of  oil  or  water.  The  upper  step-block  has 
two  dowel-pins,  also  a  key  which  fits  into  a  slot  across 
the  bottom  end  of  the  shaft. 

The  upper  side  of  the  top  block  is  counterbored  to 
fit  the  end  of  the  shaft.  The  counterbore  centers  the 
block.  The  dowel-pins  steer  the  key  into  the  key- 
way  across  the  end  of  the  shaft,  and  the  key  compels 
the  block  to  turn  with  the  shaft.  There  is  also  a 
threaded  hole  in  the  under  side  of  the  top  block.  This 


CURTIS   STEAM   TURBINE   IN    PRACTICE 


OUT)  ain 


On  Supply 


FIG.  3 


CURTIS   STEAM  TURBINE  IN  PRACTICE  7 

is  for  the  introduction  of  a  screw  which  is  used  to  pull 
the  top  block  off  the  end  of  the  shaft.  If  taken  off 
at  all  it  must  be  pulled,  for  the  dowel-pins,  key  and 
counterbore  are  close  fits.  Two  long  bolts  with  threads 


FIG.    4 

the  whole  length  are  used  if  it  becomes  necessary  to 
take  down  the  step  or  other  parts  of  the  bottom  of 
the  machine.  Two  of  the  bolts  holding  the  cover- 
pla-te  in  place  are  removed,  these  long  bolts  put  in 
their  places  and  the  nuts  screwed  up  against  the  plate 
to  hold  it  while  the  remaining  bolts  are  removed. 


8  STEAM  TURBINES 

How  TO  LOWER  STEP-BEARINGS  TO  EXAMINE  THEM 

Now,  suppose  it  is  intended  to  take  down  the  step- 
bearings  for  examination.  The  first  thing  to  do  is  to 
provide  some  way  of  holding  the  shaft  up  in  its  place 
while  we  take  its  regular  support  from  under  it.  In 
some  machines,  inside  the  base,  there  is  what  is  called 
a  "jacking  ring."  It  is  simply  a  loose  collar  on  the 
shaft,  which  covers  the  holes  into  which  four  plugs 
are  screwed.  These  are  taken  out  and  in  their  places 
are  put  four  hexagonal-headed  screws  provided  for  the 
purpose,  which  are  screwed  up.  This  brings  the  ring 
against  a  shoulder  on  the  shaft  and  then  the  cover- 
plate  and  step  may  be  taken  down. 

While  all  the  machines  have  the  same  general  appear- 
ance, there  are  some  differences  in  detail  which  may 
be  interesting.  One  difference  is  due  to  the  sub-base 
which  is  used  with  the  oil-lubricated  step-bearings. 
This  style  of  machine  has  the  jacking  ring  spoken  of, 
while  others  have  neither  sub-base  nor  jacking  ring, 
and  when  necessary  to  take  down  the  step  a  different 
arrangement  is  used. 

A  piece  of  iron  that  looks  like  a  big  horseshoe  (Fig.  5) 
is  used  to  hold  the  shaft  up.  The  flange  that  covers 
the  entrance  to  the  exhaust  base  is  taken  off  and  a 
man  goes  in  with  the  horseshoe-shaped  shim  and  an 
electric  light.  Other  men  take  a  long-handled  wrench 
and  turn  up  the  step-screw  until  the  man  inside  the 
base  can  push  the  horseshoe  shim  between  the  shoulder 
on  the  shaft  and  the  guide-bearing  casing.  The  men 
on  the  wrench  then  back  off  and  the  horseshoe  shim 


CURTIS  STEAM  TURBINE  IN  PRACTICE  9 

supports  the  weight  of  the  machine.  When  the  shim 
is  in  place,  or  the  jacking  ring  set  up,  whichever  the 
case  may  be,  the  cover-plate  bolts  may  be  taken  out, 
the  nuts  on  the  long  screws  holding  the  cover  in  place. 
The  f-inch  pipe  which  passes  up  through  the  step- 
screw  is  taken  down  and,  by  means  of  the  nuts  on  the 
long  screws,  the  cover-plate  is  lowered  about  2  inches. 
Then  through  the  hole  in  the  step-screw  a  f-inch  rod 
with  threads  on  both  ends  is  passed  and  screwed  into 


FIG.  5 

the  top  step;  then  the  cover-plate  is  blocked  so  it 
cannot  rise  and,  with  a  nut  on  the  lower  end  of  the 
f-inch  rod,  the  top  step  is  pulled  down  as  far  as  it 
will  come.  The  cover-plate  is  let  down  by  means  of 
the  two  nuts,  and  the  top  step-block  follows.  When 
it  is  lowered  to  a  convenient  hight  it  can  be  examined, 
and  the  lower  end  of  the  shaft  and  guide-bearing  will 
be  exposed  to  view. 

The  lower  guide-bearing  (Fig.  6)  is  simply  a  sleeve 
flanged  at  one  end,  babbitted  on  the  inside,  and  slightly 


JO 


STEAM  TURBINES 


tapered  on  the  outside  where  it  fits  into  the  base.  The 
flange  is  held  securely  in  the  base  by  eight  f-inch  cap- 
screws.  Between  the  cap-screw  holes  are  eight  holes 


no.  6 


CURTIS  STEAM  TURBINE  IN  PRACTICE  n 

tapped  to  1-inch,  and  when  it  is  desired  to  take  the 
bearing  down  the  cap-screws  are  taken  out  of  the  base 
and  screwed  into  the  threaded  holes  and  used  as  jacks 
to  force  the  guide-bearing  downward.  Some  pro- 
vision should  be  made  to  prevent  the  bearing  from 
coming  down  "on  the  run,"  for  being  a  taper  fit  it 
has  only  to  be  moved  about  one-half  inch  to  be  free. 
Two  bolts,  about  8  inches  long,  screwed  into  the  holes 
that  the  cap-screws  are  taken  from,  answer  nicely,  as 
a  drop  that  distance  will  not  do  any  harm,  and  the 
bearing  can  be  lowered  by  hand,  although  it  weighs 
about  200  pounds. 

The  lower  end  of  the  shaft  is  covered  by  a  removable 
bushing  which  is  easily  inspected  after  the  guide-bear- 
ing has  been  taken  down.  If  it  is  necessary  to  take 
off  this  bushing  it  is  easily  done  by  screwing  four  f- 
inch  bolts,  each  about  2  feet  long,  into  the  tapped 
holes  in  the  lower  end  of  the  bushing,  and  then  pulling 
it  off  with  a  jack.  (See  Fig.  7.) 

Each  pipe  that  enters  the  passage  in  the  foundation 
should  be  connected  by  two  unions,  one  as  close  to 
the  machine  as  possible  and  the  other  close  to  the 
foundation.  This  allows  the  taking  down  of  all  piping 
in  the  passage  completely  and  quickly  without  disturb- 
ing either  threads  or  lengths. 

STUDYING  THE  BLUEPRINTS 

Fig.  8  shows  an  elevation  and  part-sectional  view 
of  a  1 500-kilowatt  Curtis  steam  turbine.  If  one  should 
go  into  the  exhaust  base  of  one  of  these  turbines,  all 
that  could  be  seen  would  be  the  under  side  of  the 


STEAM  TURBINES 


CURTIS  STEAM  TURBINfE  JJJ  PRACTICE          13 


I4  STEAM  TURBINES 

lower  or  fourth-stage  wheel,  with  a  few  threaded  holes 
for  the  balancing  plugs  which  are  sometimes  used. 
The  internal  arrangement  is  clearly  indicated  by  the 
illustration,  Fig.  8.  It  will  be  noticed  that  each  of 
the  four  wheels  has  an  upper  and  a  lower  row  of  buckets 
and  that  there  is  a  set  of  stationary  buckets  for  each 
wheel  between  the  two  rows  of  moving  buckets.  These 
stationary  buckets  are  called  intermediates,  and  are 
counterparts  of  the  moving  buckets.  Their  sole  office 
is  to  redirect  the  steam  which  has  passed  through  the 
upper  buckets  into  the  lower  ones  at  the  proper  angle. 

The  wheels  are  kept  the  proper  distance  apart  by 
the  length  of  hub,  and  all  are  held  together  by  the  large 
nut  on  the  shaft  above  the  upper  wheel.  Each  wheel 
is  in  a  separate  chamber  formed  by  the  diaphragms 
which  rest  on  ledges  on  the  inside  of  the  wheel-case, 
their  weight  and  steam  pressure  on  the  upper  side 
holding  them  firmly  in  place  and  making  a  steam-tight 
joint  where  they  rest.  At  the  center,  where  the  hubs 
pass  through  them,  there  is  provided  a  self-centering 
packing  ring  (Fig.  9),  which  is  free  to  move  sidewise, 
but  is  prevented  from  turning,  by  suitable  lugs.  This 
packing  is  a  close  running  fit  on  the  hubs  of  the  wheel 
and  is  provided  with  grooves  (plainly  shown  in  Fig.  9) 
which  break  up  and  diminish  the  leakage  of  steam 
around  each  hub  from  one  stage  to  the  next  lower. 
Each  diaphragm,  with  the  exception  of  the  top  one, 
carries  the  expanding  nozzles  for  the  wheel  immediately 
below. 

The  expanding  nozzles  and  moving  buckets  con- 
stantly increase  in  size  and  number  from  the  top 


CURTIS  STEAM  TURBINE  IN  PRACTICE 


toward  the  bottom.  This  is  because  the  steam  volume 
increases  progressively  from  the  admission  to  the  ex- 
haust and  the  entire  expansion  is  carried  out  in  the 
separate  sets  of  nozzles,  very  much  as  if  it  were  one 
continuous  nozzle;  but  with  this  difference,  not  all  of 
the  energy  is  taken  out  of  the  steam  in  any  one  set  of 
nozzles.  The  idea  is  to  keep  the  velocity  of  the  steam 
in  each  stage  as  nearly  constant  as  possible.  The 
nozzles  in  the  diaphragms  and  the  intermediates  do 


FIG.    9 

not,  except  in  the  lowest  stage,  take  up  the  entire 
circumference,  but  are  proportioned  to  the  progressive 
expansion  of  steam  as  it  descends  toward  the  condenser. 

CLEARANCE 

.  While  the  machine  is  running  it  is  imperative  that 
there  be  no  rubbing  contact  between  the  revolving 
and  stationary  parts,  and  this  is  provided  for  by  the 
clearance  between  the  rows  of  moving  buckets  and  the 
intermediates.  Into  each  stage  of  the  machine  a 
2-inch  pipe  hole  is  drilled  and  tapped.  Sometimes  this 


l6  STEAM  TURBINES 

opening  is  made  directly  opposite  a  row  of  moving 
buckets  as  in  Fig.  10,  and  sometimes  it  is  made  oppo- 
site the  intermediate.  When  opposite  a  row  of  buckets, 
it  will  allow  one  to  see  the  amount  of  clearance  between 
the  buckets  and  the  intermediates,  and  between  the 
buckets  and  the  nozzles.  When  drilled  opposite  the 
intermediates,  the  clearance  is  shown  top  and  bottom 
between  the  buckets  and  intermediates.  (See  Fig.  n.) 
This  clearance  is  not  the  same  in  all  stages,  but  is 


greatest  in  the  fourth  stage  and  least  in  the  first.  The 
clearances  in  each  stage  are  nearly  as  follows:  First 
stage,  0.060  to  0.080;  second  stage,  0.080  to  o.ioo; 
third  stage,  0.080  to  o.ioo;  fourth  stage,  0.080  to 
0.200.  These  clearances  are  measured  by  what  are 
called  clearance  gages,  which  are  simply  taper  slips 
of  steel  about  i-inch  wide  accurately  ground  and 
graduated,  like  a  jeweler's  ring  gage,  by  marks  about 
J-inch  apart ;  the  difference  in  thickness  of  the  gage  is 
one-thousandth  of  an  inch  from  one  mark  to  the  next. 


CURTIS  STEAM  TURBINE  IN  PRACTICE  17 

To  determine  whether  the  clearance  is  right,  one  of 
the  2-inch  plugs  is  taken  out  and  some  marking  ma- 
terial, such  as  red  lead  or  anything  that  would  be  used 
on  a  surface  plate  or  bearing  to  mark  the  high  spots 


is  rubbed  on  the  taper  gage,  and  it  is  pushed  into  the 
gap  between  the  buckets  and  intermediates  as  far  as  it 
will  go,  and  then  pulled  out,  the  marking  on  the  gage 
showing  just  how  far  in  it  went,  and  the  nearest  mark 
giving  in  thousandths  of  an  inch  the  clearance.  This 
is  noted,  the  marking  spread  again,  and  the  gage  tried 
on  the  other  side,  the  difference  on  the  gage  showing 


l8  STEAM  TURBINES 

whether  the  wheel  is  high  or  low.  Whichever  may  be 
the  case  the  hight  is  corrected  by  the  step-bearing 
screw.  The  wheels  should  be  placed  as  nearly  in  the 
middle  of  the  clearance  space  as  possible.  By  some 
operators  the  clearance  is  adjusted  while  running,  in 
the  following  manner:  With  the  machine  running  at 
full  speed  the  step-bearing  screw  is  turned  until  the 
wheels  are  felt  or  heard  to  rub  lightly.  The  screw  is 
marked  and  then  turned  in  the  opposite  direction 
until  the  wheel  rubs  again.  Another  mark  is  made 
on  the  screw  and  it  is  then  turned  back  midway 
between  the  two  marks.  Either  method  is  safe  if  prac- 
tised by  a  skilful  engineer.  In  measuring  the  clear- 
ance by  the  first  method,  the  gage  should  be  used  with 
care,  as  it  is  possible  by  using  too  much  pressure  to 
swing  the  buckets  and  get  readings  which  could  be 
misleading.  To  an  inexperienced  man  the  taper 
gages  would  seem  preferable.  In  the  hands  of  a  man 
who  knows  what  he  is  doing  and  how  to  do  it,  a  tapered 
pine  stick  will  give  as  satisfactory  results  as  the  most 
elaborate  set  of  hardened  and  ground  clearance  gages. 
Referring  back  to  Fig.  1 1,  at  A  is  shown  one  of  the 
peep-holes,  opposite  the  intermediate  in  the  third 
stage  wheel  for  the  inspection  of  clearance.  The  taper 
clearance  gage  is  inserted  through  this  hole  both  above 
and  below  the  intermediate,  and  the  distance  which 
it  enters  registers  the  clearance  on  that  side.  This 
sketch  also  shows  plainly  how  the  shrouding  on  the 
buckets  and  the  intermediates  extends  beyond  the 
sharp  edges  of  the  buckets,  protecting  them  from 
damage  in  case  of  slight  rubbing.  In  a  very  few  cases 


CURTIS   STEAM  TURBINE  IN  PRACTICE  19 

wheels  have  been  known  to  warp  to  such  an  extent 
from  causes  that  were  not  discovered  until  too  late, 
that  adjustment  would  not  stop  the  rubbing.  In  such 
cases  the  shrouding  has  been  turned  or  faced  off  by 
a  cutting-off  tool  used  through  the  peep-hole. 

CARBON  PACKING  USED 

Where  the  shaft  passes  through  the  upper  head  of 
the  wheel-case  some  provision  must  be  made  to  pre- 
vent steam  from  the  first  stage  escaping.  This  is 
provided  for  by  carbon  packing  (Fig.  12),  which  con- 
sists of  blocks  of  carbon  in  sets  in  a  packing  case  bolted 
to  the  top  head  of  the  wheel-case.  There  are  three 
sets  of  these  blocks,  and  each  set  is  made  of  two  rings 
of  three  segments  each.  One  ring  of  segments  breaks 
joints  with  its  mate  in  the  case,  and  each  set  is  sepa- 
rated from  the  others  by  a  flange  in  the  case  in  which 
it  is  held.  In  some  cases  the  packing  is  kept  from 
turning  by  means  of  a  link,  one  end  of  which  is  fastened 
to  the  case  and  the  other  to  the  packing  holder.  Some- 
times light  springs  are  used  to  hold  the  packing  against 
the  shaft  and  in  some  the  pressure  of  steam  in  the  case 
does  this.  There  is  a  pipe,  also  shown  in  Fig.  12, 
leading  from  the  main  line  to  the  packing  case,  the 
pressure  in  the  pipe  being  reduced.  The  space  be- 
tween the  two  upper  sets  of  rings  is  drained  to  the  third 
stage  by  means  of  a  three-way  cock,  which  keeps  the 
balance  between  the  atmosphere  and  packing-case 
pressure.  The  carbon  rings  are  fitted  to  the  shaft 
with  a  slight  clearance  to  start  with,  and  very  soon  get 


STEAM   TURBINES 


a  smooth  finish,  which  is  not  only  practically  steam- 
tight  but  frictionless. 
The  carbon  ring  shown  in  Fig.  1 2  is  the  older  design. 


The  segments  are  held  against  the  flat  bearing  surface 
of  the  case  by  spiral  springs  set  in  brass  ferrules.  The 
circle  is  held  together  by  a  bronze  strap  screwed  and 


CURTIS   STEAM  TURBINE   IN   PRACTICE  21 


FIG.  13 


22  STEAM  TURBINES 

drawn  together  at  the  ends  by  springs.  Still  other 
springs  press  the  straps  against  the  surface  upon 
which  the  carbon  bears,  cutting  off  leaks  through 
joints  and  across  horizontal  surfaces  of  the  carbon. 
The  whole  ring  is  prevented  from  turning  by  a  connect- 
ing-rod which  engages  a  pin  in  the  hole,  like  those 
provided  for  the  springs. 

THE  SAFETY-STOP 

There  are  several  designs  of  safety-stop  or  speed- 
limit  devices  used  with  these  turbines,  the  simplest 
being  of  the  ring  type  shown  in  Fig.  13.  This  con- 
sists of  a  flat  ring  placed  around  the  shaft  between 
the  turbine  and  generator.  The  ring-type  emergencies 
are  now  all  adjusted  so  that  they  normally  run  con- 
centric with  the  shaft,  but  weighted  so  that  the  center 
of  gravity  is  slightly  displaced  from  the  center.  The 
centrifugal  strain  due  to  this  is  balanced  by  helical 
springs.  But  when  the  speed  increases  the  centrifugal 
force  moves  the  ring  into  an  eccentric  position,  when 
it  strikes  a  trigger  and  releases  a  weight  which,  falling, 
closes  the  throttle  and  shuts  off  the  steam  supply.  The 
basic  principle  upon  which  all  these  stops  are  designed 
is  the  same  —  the  centrifugal  force  of  a  weight  balanced 
by  a  spring  at  normal  speed.  Figs.  14,  15,  and  16  show 
three  other  types. 

THE  MECHANICAL  VALVE-GEAR 

Fig.  17  shows  plainly  the  operation  of  the  mechanical 
valve-gear.  The  valves  are  located  in  the  steam  chests, 
which  are  bolted  to  the  top  of  the  casing  directly 


CURTIS  STEAM  TURBINE  IN  PRACTICE 


23 


over  the  first  sets  of  expansion  nozzles.    The  chests, 
two  in  number,  are  on  opposite  sides  of  the  machine. 


n 


FIG.    14 


The   valve-stems   extend    upward   through   ordinary 


FIG.    15 


stuffing-boxes,  and  are  attached  to  the  notched  cross- 
heads  by  means  of  a  threaded  end  which  is  prevented 


24  STEAM  TURBINES 

from  screwing  in  or  out  by  a  compression  nut  on  the 
lower  end  of  the  cross-head.  Each  cross-head  is  actu- 
ated by  a  pair  of  reciprocating  pawls,  or  dogs  (shown 
more  plainly  in  the  enlarged  view,  Fig.  18),  one  of 


FIG.    1 6 


which  opens  the  valve  and  the  other  closes  it.  The 
several  pairs  of  pawls  are  hung  on  a  common  shaft 
which  receives  a  rocking  motion  from  a  crank  driven 
from  a  worm  and  worm-wheel  by  the  turbine  shaft. 
The  cross-heads  have  notches  milled  in  the  side  in 


CURTIS  STEAM  TURBINE  IN  PRACTICE 


26  STEAM  TURBINES 

which  the  pawls  engage  to  open  or  close  thorro* 


FIG.    1 8 


this  engagement  being  determined  by  what  are  called 
shield-plates,  A  (Fig.  18),  which  are  controlled  by  the 


CURTIS   STEAM  TURBINE  IN  PRACTICE  27 

T.    These  plates  are  set,  one   a  little  ahead  of 
•r,  to  obtain  successive  opening  or  closing  of 
cs.     When  more  steam  is  required  the  shield 
;late  Allows  the  proper  pawl  to  fall  into  its  notch  in 
the  cross-head  and  lift  the  valve  from  its  seat.     If 
less  steam  is  wanted  the  shield-plate  rises  and  allows 
the  lower  pawl  to  close  the  valve  on  the  down  stroke. 
The  valves,  as  can  easily  be  seen,  are  very  simple 
affairs,  the  steam  pressure  in  the  steam  chest  holding 
the  valve  either  open  or  shut  until  it  is  moved  by  the 
pawl  on  the  rock-shaft.    The  amount  of  travel  on 
the  rock-shaft  is  fixed  by  the  design,  but  the  propor- 
tionate   travel   above   and   below  the    horizontal    is 
controlled  by  the  length  of   the  connecting-rods  from 
the  crank  to  the  rock-shaft.    There  are  besides   the 
mechanical  valve-gear  the  electric  and  hydraulic,  but 
these  will  be  left  for  a  future  article. 

THE  GOVERNOR 

The  speed  of  the  machine  is  controlled  by  the  auto- 
matic opening  and  closing  of  the  admission  valves 
under  the  control  of  a  governor  (Fig.  19),  of  the  spring- 
weighted  type  attached  directly  to  the  top  end  of 
the  turbine  shaft.  The  action  of  the  governor  depends 
on  the  balance  of  force  exerted  by  the  spring,  and 
the  centrifugal  effort  of  the  rectangular-shaped  weights 
at  the  lower  end;  the  moving  weights  acting  through 
the  knife-edge  suspension  tend  to  pull  down  the  lever 
against  the  resistance  of  the  heavy  helical  spring. 
The  governor  is  provided  with  an  auxiliary  spring  on 
the  outside  of  the  governor  dome  for  varying  the  speed 


28  STEAM  TURBINES 

while  synchronizing.  The  tension  of  the  auxiliary 
spring  is  regulated  by  a  small  motor  wired  to  the 
switchboard.  This  spring  should  be  used  only  to 
correct  slight  changes  in  speed.  Any  marked  change 
should  be  corrected  by  the  use  of  the  large  hexagonal 
nut  in  the  upper  plate  of  the  governor  frame.  This 


FIG.    19 

nut  is  screwed  down  to  increase  the  speed,  and  upward 
to  decrease  it. 

THE  STAGE  VALVES 

Fig.  20  represents  one  of  the  several  designs  of 
stage  valve,  sometimes  called  the  overload  valve, 
the  office  of  which  is  to  prevent  too  high  pressure  in 
the  first  stage  in  case  of  a  sudden  overload,  and  to 


CURTIS  STEAM  TURBINE  IN  PRACTICE 


29 


transfer  a  part  of  the  steam  to  a  special  set  of  expand- 
ing nozzles  over  the  second-stage  wheel.  This  valve 
is  balanced  by  a  spring  of  adjustable  tension,  and  is, 
or  can  be,  set  to  open  and  close  within  a  very  small 


First  Stage 


Second  Stage 


Third  Stage 


predetermined  range  of  first-stage  pressure.  The 
valve  is  intended  to  open  and  close  instantly,  and 
to  supply  or  cut  off  steam  from  the  second  stage, 
without  affecting  the  speed  regulation  or  economy  of 


30  STEAM  TURBINES 

operation.     If  any  leaking  occurs  past  the  valve  it 
is  taken  care  of  by  a  drip-pipe  to  the  third  stage. 

The  steam  which  passes  through  the  automatic 
stage  valves  and  is  admitted  to  the  extra  set  of  nozzles 
above  the  second-stage  wheel  acts  upon  this  wheel 
just  the  same  as  the  steam  which  passes  through  the 
regular  second-stage  nozzles;  i.e.,  all  the  steam  which 
goes  through  the  machine  tends  to  hasten  its  speed, 
or,  more  accurately,  does  work  and  maintains  the  speed 
of  the  machine. 


II 


SETTING  THE   VALVES   OF   THE 
CURTIS  TURBINE1 

UNDER  some  conditions  of  service  the  stage  valve 
in  the  Curtis  turbine  will  not  do  what  it  is  designed 
to  do.  It  is  usually  attached  to  the  machine  in  such 
manner  that  it  will  operate  with,  or  a  little  behind, 
in  the  matter  of  time,  the  sixth  valve.  The  machine 
is  intended  to  carry  full  load  with  only  the  first  bank 
of  five  valves  in  operation,  with  proper  steam  pressure 
and  vacuum.  If  the  steam  pressure  is  under  150 
pounds,  or  the  vacuum  is  less  than  28  inches,  the  sixth 
valve  may  operate  at  or  near  full  load,  and  also  open 
the  stage  valve  and  allow  steam  to  pass  to  the  second- 
stage  nozzles  at  a  much  higher  rate  of  speed  than  the 
steam  which  has  already  done  some  work  in  the  first- 
stage  wheel.  The  tendency  is  to  accelerate  unduly 
the  speed  of  the  machine.  This  is  corrected  by  the 
governor,  but  the  correction  is  usually  carried  too  far 
and  the  machine  slows  down.  With  the  stage  valve 
in  operation,  at  a  critical  point  the  regulation  is  un- 
certain and  irregular,  and  its  use  has  to  be  abandoned. 
The  excess  first-stage  pressure  will  then  be  taken  care 
of  by  the  relief  valve,  which  is  an  ordinary  spring 

1  Contributed  to  Power  by  F.  L.  Johnson. 
31 


32  STEAM  TURBINES 

safety  valve   (not  pop)  which  allows  the  steam  to 
blow  into  the  atmosphere. 

The  mechanical  valve-gear  does  not  often  get  out 
of  order,  but  sometimes  the  unexpected  happens.  The 
shop  man  may  not  have  properly  set  up  the  nuts  on 
the  valve-stems;  or  may  have  fitted  the  distance  bush- 
ings between  the  shield  plates  too  closely;  the  super- 
heat of  the  steam  may  distort  the  steam  chest  slightly 
and  produce  friction  that  will  interfere  with  the  regula- 
tion. If  any  of  the  valve-stems  should  become  loose 
in  the  cross-heads  they  may  screw  themselves  either 
in  or  out.  If  screwed  out  too  far,  the  valve-stem 
becomes  too  long  and  the  pawl  in  descending  will, 
after  the  valve  is  seated,  continue  downward  until  it 
has  broken  something.  If  screwed  in,  the  cross-head 
will  be  too  low  for  the  upper  pawl  to  engage  and  the 
valve  will  not  be  opened.  This  second  condition  is 
not  dangerous,  but  should  be  corrected.  The  valve- 
stems  should  be  made  the  right  length,  and  all  check- 
nuts  set  up  firmly.  If  for  any  purpose  it  becomes 
necessary  to  "set  the  valves"  on  a  1 5oo-kilowatt 
mechanical  gear,  the  operator  should  proceed  in  the 
following  manner. 

SETTING  THE  VALVES  OF  A   ^OO-KILOWATT  CURTIS 
TURBINE 

We  will  consider  what  is  known  as  the  "mechanical" 
valve-gear,  with  two  sets  of  valves,  one  set  of  five 
valves  being  located  on  each  side  of  the  machine. 

In  setting  the  valves  we  should  first  "throw  out"  all 
pawls  to  avoid  breakage  in  case  the  rods  are  not  already 


SETTING  VALVES   OF  CURTIS  TURBINE 


33 


of  proper  length,  holding  the  pawls  out  by  slipping  the 
ends  of  the  pawl  springs  over  the  points  of  the  pawls, 
as  seen  in  Fig.  21.  Then  turn  the  machine  slowly  by 
hand  until  the  pawls  on  one  set  of  valves  are  at  their 
highest  point  of  travel,  then  with  the  valves  wide 
open  adjust  the  drive-rods,  i.e.,  the  rods  extending 
from  the  crank  to  the  rock-shaft,  so  that  there  is  fa 
of  an  inch  clearance  (shown  dotted  in  Fig.  17,  Chap,  I) 


at  the  point  of  opening  of  the  pawls  when  they  are 
"in."  (See  Fig.  22.)  Then  set  up  the  check-nuts 
on  the  drive-rod.  Turn  the  machine  slowly,  until  the 
pawls  are  at  their  lowest  point  of  travel.  Then,  with 
the  valves  closed,  adjust  each  valve-stem  to  give  fa 
of  an  inch  clearance  at  the  point  of  closing  of  the 
pawls  when  they  are  "in,"  securely  locking  the  check- 
nut  as  each  valve  is  set.  Repeat  this  operation  on 
the  other  side  of  the  machine  and  we  are  ready  to 


34 


STEAM  TURBINES 


SETTING  VALVES   OF  CURTIS  TURBINE          35 

adjust  the  governor-rods.  (Valves  cannot  be  set  on 
both  sides  of  the  machine  at  the  same  time,  as  the 
pawls  will  not  be  in  the  same  relative  position,  due  to 
the  angularity  of  the  drive-rods.) 

Next,  with  the  turbine  running,  and  the  synchroniz- 
ing spring  in  mid-position,  adjust  the  governor-rods 
so  that  the  turbine  will  run  at  the  normal  speed  of 
900  revolutions  per  minute  when  working  on  the  fifth 
valve,  and  carrying  full  load.  The  governor-rods  for 
the  other  side  of  the  turbine  (controlling  valves  Nos.  6 
to  10)  should  be  so  adjusted  that  the  speed  change 
between  the  fifth  and  sixth  valves  will  not  be  more 
than  three  or  four  revolutions  per  minute. 

The  valves  of  these  turbines  are  all  set  during  the 
shop  test  and  the  rods  trammed  with  an  8-inch  tram. 
Governors  are  adjusted  for  a  speed  range  of  2  per 
cent,  between  no  load  and  full  load  (1500  kilowatt), 
or  4  per  cent,  between  the  mean  speeds  of  the  first 
and  tenth  valves  (no  load  to  full  overload  capacity). 

The  rods  which  connect  the  governor  with  the  valve- 
gear  have  ordinary  brass  ends  or  heads  and  are 
adjusted  by  right-and-left  threads  and  secured  by  lock- 
nuts.  They  are  free  fits  on  the  pins  which  pass  through 
the  heads,  and  no  friction  is  likely  to  occur  which  will 
interfere  with  the  regulation,  but  too  close  work  on 
the  shield-plate  bushings,  or  a  slight  warping  of  the 
steam  chest,  will  often  produce  friction  which  will 
seriously  impair  the  regulation.  If  it  is  noticed  that 
the  shield-plate  shaft  has  any  tendency  to  oscillate 
in  unison  with  the  rock-shaft  which  carries  the  pawls, 
it  is  a  sure  indication  that  the  shield-plates  are  not  as 


36  STEAM  TURBINES 

free  as  they  should  be,  and  should  be  attended  to. 
The  governor-rod  should  be  disconnected,  the  pawls 
thrown  out  and  the  pawl  strings  hooked  over  the  ends. 

The  plates  should  then  be  rocked  up  and  down  by 
hand  and  the  friction  at  different  points  noted.  The 
horizontal  rod  at  the  back  of  the  valve-gear  may  be 
loosened  and  the  amount  of  end  play  of  each  individual 
shield-plate  noticed  and  compared  with  the  bushings 
on  the  horizontal  rod  at  the  back  which  binds  the 
shield-plates  together.  If  the  plates  separately  are 
found  to  be  perfectly  free  they  may  be  each  one  pushed 
hard  over  to  the  right  or  left  and  wedged;  then  each 
bushing  tried  in  the  space  between  the  tail-pieces  of 
the  plates.  It  will  probably  be  found  that  the  bush- 
ings are  not  of  the  right  length,  due  to  the  alteration 
of  the  form  of  the  steam  chest  by  heat.  It  will  gen- 
erally be  found  also  that  the  bushings  are  too  short, 
and  that  the  length  can  be  corrected  by  very  thin 
washers  of  sheet  metal.  It  has  been  found  in  some 
instances  that  the  thin  bands  coming  with  sectional 
pipe  covering  were  of  the  right  thickness. 

After  the  length  of  the  bushings  is  corrected  the 
shield-plates  may  be  assembled,  made  fast  and  tested 
by  rocking  them  up  and  down,  searching  for  signs  of 
sticking.  If  none  occurs,  the  work  has  been  correctly 
done,  and  there  will  be  no  trouble  from  poor  regulation 
due  to  friction  of  the  shield-plates. 

THE  BAFFLER 

The  water  which  goes  to  the  step-bearing  passes 
through  a  baffler,  the  latest  type  of  which  is  shown  by 


SETTING   VALVES   OF   CURTIS   TURBINE 


37 


Fig.  23.  It  is  a  device  for  restricting  the  flow  of  water 
or  oil  to  the  step-  and  guide-bearing.  The  amount 
of  water  necessary  to  float  the  machine  and  lubricate 
the  guide-bearing  having  been  determined  by  calcula- 
tion and  experiment,  the  plug  is  set  at  that  point 


FIG.    23 

which  will  give  the  desired  flow.  The  plug  is  a  square- 
threaded  worm,  the  length  of  which  and  the  distance 
which  it  enters  the  barrel  of  the  baffler  determining 
the  amount  of  flow.  The  greater  the  number  of  turns 
which  the  water  must  pass  through  in  the  worm  the 
less  will  flow  against  the  step-pressure. 


38  STEAM  TURBINES 

The  engineers  who  have  settled  upon  the  flow  and 
the  pressure  decided  that  a  flow  of  from  4^-  to  5^ 
gallons  per  minute  and  a  step-pressure  of  from  425 
to  450  pounds  is  correct.  These  factors  are  so  de- 
pendent upon  each  other  and  upon  the  conditions  of 
the  step-bearing  itself  that  they  are  sometimes  diffi- 
cult to  realize  in  every-day  work;  nor  is  it  necessary. 
If  the  machine  turns  freely  with  a  lower  pressure  than 
that  prescribed  by  the  engineers,  there  is  no  reason 
for  raising  this  pressure;  and  there  is  only  one  way  of 
doing  it  without  reducing  the  area  of  the  step-bearing, 
and  that  is  by  obstructing  the  flow  of  water  in  the 
step-bearing  itself. 

A  very  common  method  used  is  that  of  grinding. 
The  machine  is  run  at  about  one-third  speed  and  the 
step-water  shut  off  for  15  or  20  seconds.  This  causes 
grooves  and  ridges  on  the  faces  of  the  step-bearing 
blocks,  due  to  their  grinding  on  each  other,  which 
obstruct  the  flow  of  water  between  the  faces  and  thus 
raises  the  pressure.  It  seems  a  brutal  way  of  getting 
a  scientific  result,  if  the  result  desired  can  be  called 
scientific.  The  grooving  and  cutting  of  the  step- 
blocks  will  not  do  any  harm,  and  in  fact  they  will  aid 
in  keeping  the  revolving  parts  of  the  machine  turn- 
ing about  its  mechanical  center. 

The  operating  engineer  will  be  very  slow  to  see  the 
utility  of  the  baffler,  and  when  he  learns,  as  he  will 
sometime,  that  the  turbine  will  operate  equally  well 
with  a  plug  out  as  with  it  in  the  baffler,  he  will  be  in- 
clined to  remove  the  baffler.  It  is  true  that  with 
one  machine  operating  on  its  own  pump  it  is  possible 


SETTING  VALVES   OF  CURTIS  TURBINE          39, 

to  run  without  the  baffler,  and  it  is  also  possible  that 
in  some  particular  case  two  machines  having  identical 
step-bearing  pressures  might  be  so  operated.  The 
baffler,  however,  serves  a  very  important  function,  as 
described  more  fully  as  follows:  It  tends  to  steady 
the  flow  from  the  pump,  to  maintain  a  constant  oil 
film  as  the  pressure  varies  with  the  load,  and  when 
several  machines  are  operating  on  the  same  step-bear- 
ing system  it  is  the  only  means  which  fixes  the  flow  to 
the  different  machines  and  prevents  one  machine  from 
robbing  the  others.  Therefore,  even  if  an  engineer 
felt  inclined  to  remove  the  baffler  he  would  be  most 
liable  to  regret  taking  such  a  step. 

If  the  water  supply  should  fail  from  any  cause  and 
the  step-bearing  blocks  rub  together,  no  great  amount 
of  damage  will  result.  The  machine  will  stop  if  oper- 
ated long  under  these  conditions,  for  if  steam  pressure 
is  maintained  the  machine  will  continue  in  operation 
until  the  buckets  come  into  contact,  and  if  the  step- 
blocks  are  not  welded  together  the  machine  may  be 
started  as  soon  as  the  water  is  obtained.  If  vibration 
occurs  it  will  probably  be  due  to  the  rough  treatment 
of  the  step-blocks,  and  may  be  cured  by  homeopathic 
repeat-doses  of  grinding,  say  about  15  seconds  each. 
If  the  step-blocks  are  welded  a  new  pair  should  be 
substituted  and  the  damaged  ones  refaced. 

Some  few  experimental  steps  of  spherical  form, 
called  "saucer"  steps,  have  been  installed  with  suc- 
cess (see  Fig.  24).  They  seem  to  aid  the  lower  guide- 
bearing  in  keeping  the  machine  rotating  about  the 
mechanical  center  and  reduce  the  wear  on  the  guide- 


STEAM  TURBINES 


bearing.  In  some  instances,  too,  cast-iron  bushings 
have  been  substituted  for  bronze,  with  marked  suc- 
cess. There  seems  to  be  much  less  wear  between 


FIG.    24 

cast-iron  and  babbitt  metal  than  between  bronze  and 
babbitt  metal.  The  matter  is  really  worth  a  thorough 
investigation. 


Ill 

ALLIS-CHALMERS  COMPANY  STEAM  TURBINE 

IN  Fig.  25  may  be  seen  the  interior  construction  of 
the  steam  turbine  built  by  Allis-Chalmers  Co.,  of  Mil- 
waukee, Wis.,  which  is,  in  general,  the  same  as  the 
well-known  Parsons  type.  This  is  a  plan  view  show- 
ing the  rotor  resting  in  position  in  the  lower  half  of 
its  casing. 


FIG.    25 

Fig.  26  is  a  longitudinal  cross-section  cut  of  rotor 
and  both  lower  and  upper  casing.  Referring  to  Fig. 
26  the  steam  comes  in  from  the  steam-pipe  at  C  and 
passes  through  the  main  throttle  or  regulating  valve 
D,  which  is  a  balanced  valve  operated  by  the  gov- 
ernor. Steam  enters  the  cylinder  through  the  pas- 
sage E. 

Turning  in  the  direction  of  the  bearing  A,  it  passes 
through  alternate  stationary  and  revolving  rows  of 


42  STEAM  TURBINES 

blades,  finally  emerging  at  F  and  going  out  by  way  of 
G  to  the  condenser  or  to  atmosphere.  H,  J,  and  K 
represent  three  stages  of  blading.  L,  M,  and  Z  are 
the  balance  pistons  which  counterbalance  the  thrust 
on  the  stages  H,  J ,  and  K.  O  and  Q  are  equalizing 
pipes,  and  for  the  low-pressure  balance  piston  similar 
provision  is  made  by  means  of  passages  (not  shown) 
through  the  body  of  the  spindle. 
R  indicates  a  small  adjustable  collar  placed  inside 


FIG.    26 

the  housing  of  the  main  bearing  B  to  hold  the  spindle 
in  a  position  where  there  will  be  such  a  clearance 
between  the  rings  of  the  balance  pistons  and  those  of 
the  cylinder  as  to  reduce  the  leakage  of  steam  to  a 
minimum  and  at  the  same  time  prevent  actual  con- 
tact under  varying  temperature. 

At  5  and  T  are  glands  which  provide  a  water  seal 
against  the  inleakage  of  air  and  the  outleakage  of 
steam.  U  represents  the  flexible  coupling  to  the 
generator.  V  is  the  overload  or  by-pass  valve  used 
for  admitting  steam  to  intermediate  stage  of  the  tur- 


ALLIS-CHALMERS   STEAM   TURBINE  43 

bine.  W  is  the  supplementary  cylinder  to  contain 
the  low-pressure  balance  piston.  X  and  Y  are  refer- 
ence letters  used  in  text  of  this  chapter  to  refer  to 
equalizing  of  steam  pressure  on  the  low-pressure 
stage  of  the  turbine.  The  first  point  to  study  in  this 
construction  is  the  arrangement  of  "dummies"  L,  M, 
and  Z.  These  dummy  rings  serve  as  baffles  to  pre- 
vent steam  leakage  past  the  pistons,  and  their  contact 
at  high  velocity  means  not  only  their  own  destruction, 
but  also  damage  to  or  the  wrecking  of  surrounding 
parts.  A  simple  but  effective  method  of  eliminating 
this  difficulty  is  found  in  the  arrangement  illustrated 
in  this  figure.  The  two  smaller  balance  pistons,  L 
and  M,  are  allowed  to  remain  on  the  high-pressure 
end;  but  the  largest  piston,  Z,  is  placed  upon  the 
low-pressure  end  of  the  rotor  immediately  behind  the 
last  ring  of  blades,  and  working  inside  of  the  supple- 
mentary cylinder  W.  Being  backed  up  by  the  body  of 
the  spindle,  there  is  ample  stiffness  to  prevent  warp- 
ing. This  balance  piston,  which  may  also  be  plainly 
seen  in  Fig.  25,  receives  its  steam  pressure  from  the 
same  point  as  the  piston  M,  but  the  steam  pressure, 
equalized  with  that  on  the  third  stage  of  the  blading, 
X,  is  through  holes  in  the  webs  of  the  blade-carrying 
rings.  Entrance  to  these  holes  is  through  the  small 
annular  opening  in  the  rotor,  visible  in  Fig.  25  between 
the  second  and  third  barrels.  As,  in  consequence  of 
varying  temperatures,  there  is  an  appreciable  differ- 
ence in  the  endwise  expansion  of  the  spindle  and  cylin- 
der, the  baffling  rings  in  the  low-pressure  balance 
piston  are  so  made  as  to  allow  for  this  difference. 


44 


STEAM  TURBINES 


The  high-pressure  end  of  the  spindle  being  held  by 
the  collar  bearing,  the  difference  in  expansion  mani- 
fests itself  at  the  low-pressure  end.  The  labyrinth 
packing  of  the  high-pressure  and  intermediate  pis- 
tons has  a  small  axial  and  large  radial  clearance, 
whereas  the  labyrinth  packing  of  the  piston  Z  has, 
vice  versa,  a  small  radial  and  large  axial  clearance. 
Elimination  of  causes  of  trouble  with  the  low-pres- 
sure balance  piston  not  only  makes  it  possible  to 
reduce  the  diameter  of  the  cylinder,  and  prevent  dis- 
tortion, but  enables  the  entire  spindle  to  be  run  with 
sufficiently  small  clearance  to  obviate  any  excessive 
leakage  of  steam. 

DETAIL  OF  BLADE  CONSTRUCTION 

In  this  construction  the  blades  are  cut  from  drawn 
.  stock,  so  that  at  its  root  it  is  of  angular  dovetail  shape, 
while  at  its  tip  there  is  a  projection.  To  hold  the 
roots  of  the'  blades  firmly,  a  foundation  ring  is  pro- 
vided, as  shown  at  A  in  Fig.  27.  This  foundation 
ring  is  first  formed  to  a  circle  of  the  proper  diameter, 
and  then  slots  are  cut  in  it.  These  slots  are  accurately 
spaced  and  inclined  to  give  the  right  pitch  and  angle 
to  the  blades  (Fig.  28),  and  are  of  dovetail  shape  to 
receive  the  roots  of  the  blades.  The  tips  of  the  blades 
are  substantially  bound  together  and  protected  by 
means  of  a  channel-shaped  shroud  ring,  illustrated  in 
Fig.  31  and  at  B  in  Fig.  27.  Fig.  3 1  shows  the  cylinder 
blading  separate,  and  Fig.  27  shows  both  with  the 
shrouding.  In  these,  holes  are  punched  to  receive 


ALLIS-CHALMERS  STEAM  TURBINE  45 


FIG.   27 


46 


STEAM  TURBINES 


the  projections  on  the  tips  of  the  blades,  which  are 
rivetted  over  pneumatically. 

The  foundation  rings  themselves  are  of  dovetail 
shape  in  cross-section,  and,  after  receiving  the  roots 
of  the  blades,  are  inserted  in  dovetailed  grooves  in 
the  cylinder  and  rotor,  where  they  are  firmly  held  in 
place  by  keypieces,  as  may  be  seen  at  C  in  Fig.  27. 
Each  keypiece,  when  driven  in  place,  is  upset  into 
an  undercut  groove,  indicated  by  D  in  Fig.  27,  thereby 
positively  locking  the  whole  structure  together.  Each 


FIG.    28 

separate  blade  is  firmly  secured  by  the  dovetail  shape 
of  the  root,  which  is  held  between  the  corresponding 
dovetailed  slot  in  the  foundation  ring  and  the  under- 
cut side  of  the  groove. 

Fig.  29,  from  a  photograph  of  blading  fitted  in  a 
turbine,  illustrates  the  construction,  besides  showing 
the  uniform  spacing  and  angles  of  the  blades. 

The  obviously  thin  flanges  of  the  shroud  rings  are 
purposely  made  in  that  way,  so  that,  in  case  of  acci- 
dental contact  between  revolving  and  stationary 
parts,  they  will  wear  away  enough  to  prevent  the 


C  r  r   r  ^ 


4§  STEAM  TURBINES 

blades  from  being  ripped  out.  This  protection,  how- 
ever, is  such  that  to  rip  them  out  a  whole  half  ring 
of  blades  must  be  sheared  off  at  the  roots.  The 
strength  of  the  blading,  therefore,  depends  not  upon 
the  strength  of  an  individual  blade,  but  upon  the  com- 
bined shearing  strength  of  an  entire  ring  of  blades. 
The  blading  is  made  up  and  inserted  in  half  rings, 


FIG.  30 


and  Fig.  30  shows  two  rings  of  different  sizes  ready  to 
be  put  in  place.  Fig.  3 1  shows  a  number  of  rows  of 
blading  inserted  in  the  cylinder  of  an  Allis-Chalmers 
steam  turbine,  and  Fig.  32  gives  view  of  blading  in 
the  same  turbine  after  nearly  three  years'  running. 


THE  GOVERNOR 


Next  in  importance  to  the  difference  in  blading  and 
balance  piston  construction,  is  the  governing  mechan- 


ALLIS-CHALMERS   STEAM   TURBINE 


49 


ism  used  with  these  machines.  This  follows  the  well- 
known  Hartung  type,  which  has  been  brought  into 
prominence  heretofore  largely  in  connection  with 


FIG.   31 


hydraulic  turbines;  and  the  governor,  driven  directly 
from  the  turbine  shaft  by  means  of  cut  gears  working 
in  an  oil  bath,  is  required  to  operate  the  small,  bal- 
anced oil  relay-valve  only,  while  the  two  steam  valves, 
main  and  by-pass  (or  overload),  are  controlled  by  an 


STEAM  TURBINES 


oil  pressure  of  about  20  pounds  per  square  inch,  acting 
upon  a  piston  of  suitable  size.  In  view  of  the  fact 
that  a  turbine  by-pass  valve  opens  only  when  the 
unit  is  required  to  develop  overload,  or  the  vacuum 


fails,  a  good  feature  of  this  governing  mechanism  is 
that  the  valve  referred  to  can  be  kept  constantly  in 
motion,  thereby  preventing  sticking  in  an  ermer- 
gency,  even  though  it  be  actually  called  into  action 
only  at  long  intervals.  Another  feature  of  impor- 


ALLIS-CHALMERS  STEAM  TURBINE  51 

tance  is  that  the  oil  supply  to  the  bearings,  as  well  as 
that  to  the  governor,  can  be  interconnected  so  that 
the  governor  will  automatically  shut  off  the  steam  if 
the  oil  supply  fails  and  endangers  the  bearings.  This 
mechanism  is  also  so  proportioned  that,  while  respond- 
ing quickly  to  variations  in  load,  its  sensitiveness  is 
kept  within  such  bounds  as  to  secure  the  best  results 
in  the  parallel  operation  of  alternators.  The  gover- 
nor can  be  adjusted  for  speed  while  the  turbine  is  in 
operation,  thereby  facilitating  the  synchronizing  of 
alternators  and  dividing  the  load  as  may  be  desired. 
In  order  to  provide  for  any  possible  accidental  de- 
rangement of  the  main  governing  mechanism,  an 
entirely  separate  safety  or  over-speed  governor  is 
furnished.  This  governor  is  driven  directly  by  the 
turbine  shaft  without  the  intervention  of  gearing,  and 
is  so  arranged  and  adjusted  that,  if  the  turbine  should 
reach  a  predetermined  speed  above  that  for  which  the 
main  governor  is  set,  the  safety  governor  will  come 
into  action  and  trip  a  valve  which  entirely  shuts  off 
the  steam  supply,  bringing  the  turbine  to  a  stop. 

LUBRICATION 

Lubrication  of  the  four  bearings,  which  are  of  the 
self-adjusting,  ball  and  socket  pattern,  is  effected  by 
supplying  an  abundance  of  oil  to  the  middle  of  each 
bearing  and  allowing  it  to  flow  out  at  the  ends.  The 
oil  is  passed  through  a  tubular  cooler,  having  water 
circulation,  and  pumped  back  to  the  bearings.  Fig. 
33  shows  the  entire  arrangement  graphically  and 
much  more  clearly  than  can  be  explained  in  words. 


STEAM  TURBINES 


ALLIS-CHALMERS   STEAM   TURBINE     .  53 

The  oil  is  circulated  by  a  pump  directly  operated 
from  the  turbine,  except  where  the  power-house  is 
provided  with  a  central  oiling  system.  Particular 
stress  is  laid  by  the  builders  upon  the  fact  that  it  is 
not  necessary  to  supply  the  bearings  with  oil  under 
pressure,  but  only  at  a  head  sufficient  to  enable  it  to 
run  to  and  through  the  bearings;  this  head  never 
exceeding  a  few  feet.  With  each  turbine  is  installed 
a  separate  direct-acting  steam  pump  for  circulating 
oil  for  starting  up.  This  will  be  referred  to  again 
under  the  head  of  operating. 

GENERATOR 

The  turbo-generator,  which  constitutes  the  elec- 
trical end  of  this  unit,  is  totally  enclosed  to  provide 
for  noiseless  operation,  and  forced  ventilation  is  se- 
cured by  means  of  a  small  fan  carried  by  the  shaft  on 
each  end  of  'the  rotor.  The  air  is  taken  in  at  the  ends 
of  the  generator,  passes  through  the  fans  and  is  dis- 
charged over  the  end  connections  of  the  armature 
coils  into  the  bottom  of  the  machine,  whence  it  passes 
through  the  ventilating  ducts  of  the  core  to  an  open- 
ing at  the  top.  The  field  core  is,  according  to  size, 
built  up  either  of  steel  disks,  each  in  one  piece,  or  of 
steel  forgings,  so  as  to  give  high  magnetic  permeabil- 
ity and  great  strength.  The  coils  are  placed  in  radial 
slots,  thereby  avoiding  side  pressure  on  the  slot  insu- 
lation and  the  complex  stresses  resulting  from  cen- 
trifugal force,  which,  in  these  rotors,  acts  normal  to 
the  flat  surface  of  the  strip  windings. 


54  STEAM  TURBINES 

OPERATION 

As  practically  no  adjustments  are  necessary  when 
these  units  are  in  operation,  the  greater  part  of  the 
attention  required  by  them  is  involved  in  starting  up 
and  shutting  down,  which  may  be  described  in  detail 
as  follows: 

To  Start  Up 

First,  the  auxiliary  oil  pump  is  set  going,  and  this 
is  speeded  up  until  the  oil  pressure  shows  a  hight 
sufficient  to  lift  the  inlet  valve  and  oil  is  flowing  stead- 
ily at  the  vents  on  all  bearings.  The  oil  pressure  then 
shows  about  20  to  25  pounds  on  the  "Relay  Oil" 
gage,  and  2  to  4  pounds  on  the  "Bearing  Oil"  gage. 
Next  the  throttle  is  opened,  without  admitting  suffi- 
cient steam  to  the  turbine  to  cause  the  spindle  to 
turn,  and  it  is  seen  that  the  steam  exhausts  freely 
into  the  atmosphere,  also  that  the  high-pressure  end 
of  the  turbine  expands  freely  in  its  guides.  Water 
having  been  allowed  to  blow  out  through  the  steam- 
chest  drains,  the  drains  are  closed  and  steam  is  per- 
mitted to  continue  flowing  through  the  turbine  not 
less  than  a  half  an  hour  (unless  the  turbine  is  warm 
to  start  with,  when  this  period  may  be  reduced)  still 
without  turning  the  spindle.  After  this  it  is  advisable 
to  shut  off  steam  and  let  the  turbine  stand  ten  min- 
utes, so  as  to  warm  thoroughly,  during  which  time 
the  governor  parts  may  be  oiled  and  any  air  which 
may  have  accumulated  in  the  oil  cylinder  above  the 
inlet  valve  blown  off.  Then  the  throttle  should  be 
opened  sufficiently  to  start  the  turbine  spindle  to  revol- 


ALLIS-CHALMERS  STEAM  TURBINE  55 

ving  very  slowly  and  the  machine  allowed  to  run  in 
this  way  for  five  minutes. 

Successive  operations  may  be  mentioned  briefly  as 
admitting  water  to  the  oil  cooler;  bringing  the  turbine 
up  to  speed,  at  the  same  time  slowing  down  the  aux- 
iliary oil  pump  and  watching  that  the  oil  pressures 
are  kept  up  by  the  rotary  oil  pump  on  the  turbine; 
turning  the  water  on  to  the  glands  very  gradually 
and,  before  putting  on  vacuum,  making  sure  that 
there  is  just  enough  water  to  seal  these  glands  prop- 
erly; and  starting  the  vaccuum  gradually  just  before 
putting  on  the  load.  These  conditions  having  been 
complied  with,  the  operator  next  turns  his  attention 
to  the  generator,  putting  on  the  field  current,  syn- 
chronizing carefully  and  building  up  the  load  on  the 
unit  gradually. 

The  principal  precautions  to  be  observed  are  not 
to  start  without  warming  up  properly,  to  make  sure 
that  oil  is  flowing  freely  through  the  bearings,  that 
vacuum  is  not  put  on  until  the  water  glands  seal,  and 
to  avoid  running  on  vacuum  without  load  on  the 
turbine. 

IN  OPERATION 

In  operation  all  that  is  necessary  is  to  watch  the 
steam  pressure  at  the  "Throttle"  and  "Inlet"  gages, 
to  see  that  neither  this  pressure  nor  the  steam  tem- 
perature varies  much;  to  keep  the  vacuum  constant, 
as  well  as  pressures  on  the  water  glands  and  those 
indicated  by  the  "Relay  Oil"  and  "Bearing  Oil" 
gages;  to  take  care  that  the  temperatures  of  the  oil 


56  STEAM  TURBINES 

flowing  to  and  from  the  bearings  does  not  exceed 
135  degrees  Fahr.  (at  which  temperature  the  hand 
can  comfortably  grasp  the  copper  oil-return  pipes); 
to  see  that  oil  flows  freely  at  all  vents  on  the  bearings, 
and  that  the  governor  parts  are  periodically  oiled. 
So  far  as  the  generator  is  concerned,  it  is  only  essen- 
tial to  follow  the  practice  common  in  all  electric  power 
plant  operation,  which  need  not  be  reviewed  here. 

Stopping  the  turbine  is  practically  the  reverse  of 
starting,  the  successive  steps  being  as  follows:  starting 
the  auxiliary  oil  pump,  freeing  it  of  water  and  allow- 
ing it  to  run  slowly;  removing  the  load  gradually; 
breaking  the  vacuum  when  the  load  is  almost  zero, 
shutting  off  the  condenser  injection  and  taking  care 
that  the  steam  exhausts  freely  into  the  atmosphere; 
shutting  off  the  gland  water  when  the  load  and  vac- 
uum are  off;  pulling  the  automatic  stop  to  trip  the 
valve  and  shut  off  steam  and,  as  the  speed  of  the 
turbine  decreases,  speeding  up  the  auxiliary  oil  pump 
to  maintain  pressure  on  the  bearings;  then,  when  the 
turbine  has  stopped,  shutting  down  the  auxiliary  oil 
pump,  turning  off  the  cooling  water,  opening  the  steam 
chest  drains  and  slightly  oiling  the  oil  inlet  valve- 
stem.  During  these  operations  the  chief  particulars 
to  be  heeded  are:  not  to  shut  off  the  steam  before 
starting  the  auxiliary  oil  pump  nor  before  the  vacuum 
is  broken,  and  not  to  shut  off  the  gland  water  with 
vacuum  on  the  turbine.  The  automatic  stop  should 
also  remain  unhooked  until  the  turbine  is  about  to 
be  started  up  again. 


ALLIS-CHALMERS   STEAM   TURBINE  57 

GENERAL 

Water  used  in  the  glands  of  the  turbine  must  be 
free  from  scale-forming  impurities  and  should  be 
delivered  at  the  turbine  under  a  steady  pressure  of 
not  less  than  15  pounds.  The  pressure  in  the  glands 
will  vary  from  4  to  10  pounds.  This  water  may  be 
warm.  In  the  use  of  water  for  the  cooling  coils  and 
of  oil  for  the  lubricating  system,  nothing  more  is 
required  than  ordinary  good  sense  dictates.  An  abso- 
lutely pure  mineral  oil  must  be  supplied,  of  a  non- 
foaming  character,  and  it  should  be  kept  free  through 
filtering  from  any  impurities. 

The  above  refers  particularly  to  Allis-Chalmers 
turbines  of  the  type  ordinarily  used  for  power  service. 
For  turbines  built  to  be  run  non-condensing,  the  part 
relating  to  vacuum  does  not,  of  course,  apply. 


IV 
WESTINGHOUSE-PARSONS  STEAM  TURBINE 

WHILE  the  steam  turbine  is  simple  in  design  and 
construction  and  does  not  require  constant  tinkering 
and  adjustment  of  valve  gears  or  taking  up  of  wear 
in  the  running  parts,  it  is  like  any  other  piece  of  fine 
machinery  in  that  it  should  receive  intelligent  and 
careful  attention  from  the  operator  by  inspection  of 
the  working  parts  that  are  not  at  all  times  in  plain 
view.  Any  piece  of  machinery,  no  matter  how  simple 
and  durable,  if  neglected  or  abused  will  in  time  come 
to  grief,  and  the  higher  the  class  of  the  machine  the 
more  is  this  true. 

Any  engineer  who  is  capable  of  running  and  intelli- 
gently taking  care  of  a  reciprocating  engine  can  run 
and  take  care  of  a  turbine,  but  if  he  is  to  be  anything 
more  than  a  starter  and  stopper,  it  is  necessary  that 
he  should  know  what  is  inside  of  the  casing,  what  must 
be  done  and  avoided  to  prevent  derangement,  and  to 
keep  the  machine  in  continued  and  efficient  operation. 

In  the  steam  turbine  the  steam  instead  of  being 
expanded  against  a  piston  is  made  to  expand  against 
and  to  get  up  velocity  in  itself.  The  jet  of  steam  is 
then  made  to  impinge  against  vanes  or  to  react  against 
the  moving  orifice  from  which  it  issues,  in  either  of 
58 


WESTINGHOUSE-PARSONS  TURBINE  59 

which  cases  its  velocity  and  energy  are  more  or  less 
completely  abstracted  and  appropriated  by  the  re- 
volving member.  The  Parsons  turbine  utilizes  a 
combination  of  these  two  methods. 

Fig.  34  is  a  sectional  view  of  the  standard  Westing- 
house-Parsons  single-flow  turbine.  A  photograph  of 
the  rotor  R  R  R  is  reproduced  in  Fig.  35,  while  in  Fig. 
36  a  section  of  the  blading  is  shown  upon  a  larger 
scale.  Between  the  rows  of  the  blading  upon  the 
rotor  extend  similar  rows  of  stationary  blades  attached 
to  the  casing  or  stator.  The  steam  entering  at  A 
(Fig.  34),  fills  the  circular  space  surrounding  the  rotor 
and  passes  first  through  a  row  of  stationary  blades,  i 
(Fig.  37),  expanding  from  the  initial  pressure  P  to 
the  slightly  lower  pressure  Plf  and  attaining  by  that 
expansion  a  velocity  with  which  it  is  directed  upon 
the  moving  blade  2.  In  passing  through  this  row  of 
blades  it  is  further  expanded  from  pressure  P1  to  P2 
and  helps  to  push  the  moving  blades  along  by  the  reac- 
tion of  the  force  with  which  it  issues  therefrom.  Im- 
pinging upon  the  second  row  of  stationary  blades  3, 
the  direction  of  flow  is  diverted  so  as  to  make  it  im- 
pinge at  a  favorable  angle  upon  the  second  row  of 
revolving  blades  4,  and  the  action  is  continued  until 
the  steam  is  expanded  to  the  pressure  of  the  conden- 
ser or  of  the  medium  into  which  the  turbine  finally 
exhausts.  As  the  expansion  proceeds,  the  passages 
are  made  larger  by  increasing  the  length  of  the  blades 
and  the  diameter  of  the  drums  upon  which  they  are 
carried  in  order  to  accommodate  the  increasing  vol- 
ume. 


6o 


STEAM  TURBINES 


WESTINGHOUSE-PARSONS  TURBINE  6l 


62 


STEAM  TURBINES 


WESTINGHOUSE-PARSONS  TURBINE  63 

It  is  not  necessary  that  the  blades  shall  run  close 
together,  and  the  axial  clearance,  that  is  the  space 
lengthwise  of  the  turbine  between  the  revolving  and 
the  stationary  blades,  varies  from  i  to  ^  inch;  but  in 
order  that  there  may  not  be  excessive  leakage  over 
the  tops  of  the  blades,  as  shown,  very  much  exagger- 
ated, in  Fig.  38,  the  radial  clearance,  that  is,  the  clear- 
ance between  the  tops  of  the  moving  blades  and  the 
casing,  and  between  the  ends  of  the  stationary  blades 
and  the  shell  of  the  rotor,  must  be  kept  down  to  the 


FIG.  37 

lowest  practical  amount,  and  varies,  according  to  the 
size  of  the  machine  and  length  of  blade,  from  about 
0.025  to  0-125  °f  an  mcn- 

In  the  passage  A  (Fig.  34)  exists  the  initial  pres- 
sure; in  the  passage  B  the  pressure  after  the  steam 
has  passed  the  first  section  or  diameter  of  the  rotor; 
in  the  passage  C  after  it  has  passed  the  second  sec- 
tion. The  pressure  acting  upon  the  exposed  faces 
of  the  rows  of  vanes  would  crowd  the  rotor  to  the 
left.  They  are  therefore  balanced  by  pistons  or 
"dummies"  P  P  P  revolving  with  the  shaft  and  ex- 
posing in  the  annular  spaces  B1  and  C1  the  same  areas 


STEAM  TURBINES 


as  those  of  the  blade  sections  which  they  are  designed 
to  balance.    The  same  pressure  is  maintained  in  B1 


as  in  B,  and  in  C1  as  in  C  by  connecting  them  with 
equalizing  pipes  E  E.    The  third  equalizing  pipe  con- 


WESTINGHOUSE-PARSONS  TURBINE  65 

nects  the  back  or  right-hand  side  of  the  largest  dummy 
with  the  exhaust  passage  so  that  the  same  pressure 
exists  upon  it  as  exists  upon  the  exhaust  end  of  the 
rotor.  These  dummy  pistons  are  shown  at  the  near 
end  of  the  rotor  in  Fig.  35.  They  are  grooved  so  as 
to  form  a  labyrinth  packing,  the  face  of  the  casing 
against  which  they  run  being  grooved  and  brass  strips 
inserted,  as  shown  in  Fig.  39.  The  dummy  pistons 
prevent  leakage  from  A,  Bl  and  O  to  the  condenser, 
and  must,  of  course,  run  as  closely  as  practicable  to 
the  rings  in  the  casing,  the  actual  clearance  being 


Botor 


from  about  0.005  to  0.015  of  an  inch,  again  depending 
on  the  size  of  the  machine. 

The  axial  adjustment  is  controlled  by  the  device 
shown  at  T  in  Fig.  34  and  on  a  larger  scale  in  Fig.  40. 
The  thrust  bearing  consists  of  two  parts,  7\  T2.  Each 
consists  of  a  cast-iron  body  in  which  are  placed  brass 
collars.  These  collars  fit  into  grooves  C,  turned  in 
the  shaft  as  shown.  The  halves  of  the  block  are 
brought  into  position  by  means  of  screws  Sl  S2  acting 
on  levers  Lx  L2  and  mounted  in  the  bearing  pedestal 
and  cover.  The  screws  are  provided  with  graduated 
heads  which  permit  the  respective  halves  of  the  thrust 
bearing  to  be  set  within  one  one-thousandth  of  an  inch. 


66  STEAM  TURBINES 

The  upper  screw  S2  is  set  so  that  when  the  rotor 
exerts  a  light  pressure  against  it  through  the  thrust 
block  and  lever  the  grooves  in  the  balance  pistons  are 
just  unable  to  come  in  contact  with  the  dummy  strips 
in  the  cylinder.  The  lower  screw  5t  is  then  adjusted 
to  permit  about  0.008  to  o.oio  of  an  inch  freedom 
for  the  collar  between  the  grooves  of  the  thrust 
bearing. 

These  bearings  are  carefully  adjusted  before  the 
machine  leaves  the  shop,  and  to  prevent  either  acci- 
dental or  unauthorized  changes  of  their  adjustment 
the  adjusting  screw  heads  are  locked  by  the  method 
shown  in  Fig.  40.  The  screw  cannot  be  revolved 
without  sliding  back  the  latch  L3.  To  do  this  the  pin 
P^  must  be  withdrawn,  for  which  purpose  the  bearing 
cover  must  be  removed. 

In  general  this  adjustment  should  not  be  changed 
except  when  there  has  been  some  wear  of  the  collars 
in  the  thrust  bearing;  nevertheless,  it  is  a  wise  precau- 
tion to  go  over  the  adjustment  at  intervals.  The 
method  of  doing  this  is  as  follows :  The  machine  should 
have  been  in  operation  for  some  time  so  as  to  be  well 
and  evenly  heated  and  should  be  run  at  a  reduced 
speed,  say  10  per  cent,  of  the  normal,  during  the  ac- 
tual operation  of  making  the  adjustment.  Adjust 
the  upper  screw  which,  if  tightened,  would  push 
the  spindle  away  from  the  thrust  bearing  toward  the 
exhaust.  Find  a  position  for  this  so  that  when  the 
other  screw  is  tightened  the  balance  pistons  can  just 
be  heard  to  touch,  and  so  the  least  change  of  position 
inward  of  the  upper  screw  will  cause  the  contact  to 


WESTINGHOUSE-PARSONS  TURBINE 


67 


cease.  To  hear  if  the  balance  pistons  are  touching, 
a  short  piece  of  hardwood  should  be  placed  against 
the  cylinder  casing  near  the  balance  piston.  If  the 


68  STEAM  TURBINES 

ear  is  applied  to  the  other  end  of  the  piece  of 
wood  the  contact  of  the  balance  pistons  can  be  very 
easily  detected.  The  lower  screw  should  then  be 
loosened  and  the  upper  screw  advanced  from  five 
to  fifteen  one-thousandths,  according  to  the  machine, 
at  which  position  the  latter  may  be  considered  to  be 
set.  The  lower  screw  should  then  be  advanced  until 
the  under  half  of  the  thrust  bearing  pushes  the  rotor 
against  the  other  half  of  the  thrust  bearing,  and  from 
this  position  it  should  be  pushed  back  ten  or  more 
one-thousandths,  to  give  freedom  for  the  rotor  be- 
tween the  thrusts,  and  locked.  A  certain  amount  of 
care  should  be  exercised  in  setting  the  dummies,  to 
avoid  straining  the  parts  and  thus  obtain  a  false 
setting. 

The  object  in  view  is  to  have  the  grooves  of  the  bal- 
ance pistons  running  as  close  as  possible  to  the  collars 
in  the  cylinder,  but  without  danger  of  their  coming 
in  actual  contact,  and  to  allow  as  little  freedom  as 
possible  in  the  thrust  being  itself,  but  enough  to  be 
sure  that  it  will  not  heat.  The  turbine  rotor  itself 
has  scarcely  any  end  thrust,  so  that  all  the  thrust 
bearing  has  to  do  is  to  maintain  the  above-prescribed 
adjustment. 

The  blades  are  so  gaged  that  at  all  loads  the  rotor 
has  a  very  light  but  positive  thrust  toward  the  running 
face  of  the  dummy  strips,  thus  maintaining  the  proper 
clearance  at  the  dummies  as  determined  by  the  set- 
ting of  the  proper  screw  adjustment. 


WESTINGHOUSE-PARSONS   TURBINE  69 

MAIN  BEARINGS 

The  bearings  which  support  the  rotor  are  shown 
at  F  F  in  Fig.  34  and  in  detail  in  Fig.  41.  The  bearing 
proper  consists  of  a  brass  tube  B  with  proper  oil 
grooves.  It  has  a  dowel  arm  L  which  fits  into  a  cor- 
responding recess  in  the  bearing  cover  and  which  pre- 
vents the  bearing  from  turning.  On  this  tube  are 
three  concentric  tubes,  C  D  E,  each  fitting  over  the 
other  with  some  clearance  so  that  the  shaft  is  free  to 
move  slightly  in  any  direction.  These  tubes  are  held 
in  place  by  the  nut  F,  and  this  nut,  in  turn,  is  held  by 
the  small  set-screw  G.  The  bearing  with  the  surround- 
ing tubes  is  placed  inside  of  the  cast-iron  shell  A, 
which  rests  in  the  bearing  pedestal  on  the  block  and 
liner  H.  The  packing  ring  M  prevents  the  leakage 
of  oil  past  the  bearing.  Oil  enters  the  chamber  at 
one  end  of  the  bearing  at  the  top  and  passes  through 
the  oil  grooves,  lubricating  the  journal,  and  then  out 
into  the  reservoir  under  the  bearing.  The  oil  also 
fills  the  clearance  between  the  tubes  and  forms  a 
cushion,  which  dampens  any  tendency  to  vibration. 

The  bearings,  being  supported  by  the  blocks  or 
"pads"  H,  are  self-alining.  Under  these  pads  are 
liners  5,  10,  20,  and  50  thousandths  in  thickness.  By 
means  of  these  liners  the  rotor  may  be  set  in  its  proper 
running  position  relative  to  the  stator.  This  opera- 
tion is  quite  simple.  Remove  the  liners  from  under 
one  bearing  pad  and  place  them  under  the  opposite 
pad  until  a  blade  touch  is  obtained  by  turning  the 
rotor  over  by  hand.  After  a  touch  has  been  obtained 


7o 


STEAM  TURBINES 


on  the  top,  bottom,  and  both  sides,  the  total  radial 
blade  clearance  will  be  known  to  equal  the  thickness 
of  the  liners  transferred.  The  position  of  the  rotor 


WESTINGHOUSE-PARSONS  TURBINE  71 

is  then  so  adjusted  that  the  radial  blade  clearance  is 
equalized  when  the  turbine  is  at  operating  tempera- 
ture. 

On  turbines  running  at  1800  revolutions  per  minute 
or  under,  a  split  babbitted  bearing  is  used,  as  shown  in 
Figs.  42a  and  42^.  These  bearings  are  self-alining  and 
have  the  same  liner  adjustment  as  the  concentric- 
sleeve  bearings  just  described.  Oil  is  supplied  through 
a  hole  D  in  the  lower  liner  pad,  and  is  carried  to  the 
oil  groove  F  through  the  tubes  E  E.  The  oil  flows 
from  the  middle  of  this  bearing  to  both  ends  instead 
of  from  one  end  to  the  other,  as  in  the  other  type. 

PACKING  GLANDS 

Where  the  shaft  passes  through  the  casing  at  either 
end  it  issues  from  a  chamber  in  which  there  exists  a 
vacuum.  It  is  necessary  to  pack  the  shaft  at  these 
points,  therefore,  against  the  atmospheric  pressure, 
and  this  is  done  by  means  of  a  water-gland  packing 
W  W  (Fig.  34).  Upon  the  shaft  in  Fig.  35,  just  in 
front  of  the  dummy  pistons,  will  be  seen  a  runner  of 
this  packing  gland,  which  runner  is  shown  upon  a 
larger  scale  and  from  a  different  direction  in  Fig.  43. 
To  get  into  the  casing  the  air  would  have  to  enter 
the  guard  at  A  (Fig.  44),  pass  over  the  projecting  rings 
B,  the  function  of  which  is  to  throw  off  any  water 
which  may  be  creeping  along  the  shaft  by  centrifugal 
force  into  the  surrounding  space  C,  whence  it  escapes 
by  the  drip  pipe  D,  hence  over  the  five  rings  of  the 
labyrinth  packing  E  and  thence  over  the  top  of  the 
revolving  blade  wheel,  it  being  apparent  from  Fig.  43 


72 


STEAM  TURBINES 


that  there  is  no  way  for  the  air  to  pass  by  without 
going  up  over  the  top  of  the  blades;  but  water  is 
admitted  to  the  centrally  grooved  space  through  the 


o 

OP 


\sj    m 


WESTINGHOUSE-PARSONS  TURBINE 


73 


pipe  shown,  and  is  revolved  with  the  wheel  at  such 
velocity  that  the  pressure  due  to  centrifugal  force 
exceeds  that  of  the  atmosphere,  so  that  it  is  impossible 


74 


STEAM  TURBINES 


for  the  air  to  force  the  water  aside  and  leak  in  over 
the  tips  of  the  blades,  while  the  action  of  the  runner 


FIG.  43 


in  throwing  the  water  out  would  relieve  the  pressure 
at  the  shafts  and  avoid  the  tendency  of  the  water 


WESTINGHOUSE-PARSONS  TURBINE 


75 


Water 

Inlet 


FIG.  44 


76 


STEAM   TURBINES 


to  leak  outward  through  the  labyrinth  packing  either 
into  the  vacuum  or  the  atmosphere. 

The  water  should  come  to  the  glands  under  a  head 
of  about   10  feet,  or  a  pressure  of  about  5  pounds, 
and  be  connected  in  such  a  way  that  this  pressure 
may   be   uninterruptedly   maintained.     Its    tempera- 
ture must  be  lower  than  the  temperature  due  to  the 


vacuum  within  the  turbine,  or  it  will  evaporate  read- 
ily and  find  its  way  into  the  turbine  in  the  form  of 
steam. 

In  any  case  a  small  amount  of  the  steaming  water 
will  pass  by  the  gland  collars  into  the  turbine,  so  that 
if  the  condensed  steam  is  to  be  returned  to  the  boilers 
the  water  used  in  the  glands  must  be  of  such  character 
that  it  may  be  safely  used  for  feed  water.  But 
whether  the  water  so  used  is  to  be  returned  to  the 


WESTINGHOUSE-PARSONS   TURBINE 


77 


boilers  or  not  it  should  never  contain  an  excessive 
amount  of  lime  or  solid  matter,  as  a  certain  amount 
of  evaporation  is  continually  going  on  in  the  glands 
which  will  result  in  the  deposit  of  scale  and  require 
frequent  taking  apart  for  cleaning. 

When   there   is    an   ample   supply  of  good,   clean 
water  the  glands  may  be  packed  as  in  Fig.  45,  the 


fc 


FIG.    46 

standpipe  supplying  the  necessary  head  and  the  sup- 
ply valve  being  opened  sufficiently  to  maintain  a  small 
stream  at  the  overflow.  When  water  is  expensive 
and  the  overflow  must  be  avoided,  a  small  float 
may  be  used  as  in  Fig.  46,  the  ordinary  tank  used 
by  plumbers  for  closets,  etc.,  serving  the  purpose 
admirably. 

When  the  same  water  that  is  supplied  to  the  glands 
is  used  for  the  oil-cooling  coils,  which  will  be  de- 


STEAM  TURBINES 


scribed  in  detail  later,  the  coils  may  be  attached  to 
either  of  the  above  arrangements  as  shown  in  Fig.  47. 
When  the  only  available  supply  of  pure  water  is 
that  for  the  boiler  feed,  and  the  condensed  steam  is 
pumped  directly  back  to  the  boiler,  as  shown  in  Fig. 
48,  the  delivery  from  the  condensed-water  pumps 
may  be  carried  to  an  elevation  10  feet  above  the  axis 
of  the  glands,  where  a  tank  should  be  provided  of 


FIG.  47 

sufficient  capacity  that  the  water  may  have  time  to 
cool  considerably  before  being  used.  In  most  of 
these  cases,  if  so  desired,  the  oil-cooling  water  may 
come  from  the  circulating  pumps  of  the  condenser, 
provided  there  is  sufficient  pressure  to  produce  cir- 
culation, as  is  also  shown  in  Fig.  48. 

When  the  turbine  is  required  to  exhaust  against  a 
back  pressure  of  one  or  two  pounds  a  slightly  different 
arrangement  of  piping  must  be  made.  The  water 
in  this  case  must  be  allowed  to  circulate  through  the 


WESTINGHOUSE-PARSONS  TURBINE 


79 


glands  in  order  to  keep  the  temperature  below  212 
degrees  Fahrenheit.  If  this  is  not  done  the  water 
in  the  glands  will  absorb 'heat  from  the  main  castings 
of  the  machine  and  will  evaporate.  This  evaporation 
will  make  the  glands  appear  as  though  they  were 
leaking  badly.  In  reality  it  is  nothing  more  than 


the  water  in  the  glands  boiling,  but  it  is  nevertheless 
equally  objectionable.  This  may  be  overcome  by 
the  arrangement  shown  in  Fig.  49,  where  two  con- 
nections and  valves  are  furnished  at  M  and  N,  which 
drain  away  to  any  suitable  tank  or  sewer.  These 
valves  are  open  just  enough  to  keep  sufficient  circula- 
tion so  that  there  is  no  evaporation  going  on,  which 
is  evidenced  by  steam  coming  out  as  though  the 


8o 


STEAM   TURBINES 


glands  were  leaking.     These  circulating  valves  may 
be  used  with  any  of  the  arrangements  above  described. 

THE  GOVERNOR 

On  the  right-hand  end  of  the  main  shaft  in  Fig.  34 
there  will  be  seen  a  worm  gear  driving  the  governor. 
This  is  shown  on  a  larger  scale  at  A  (Fig.  50).  At 
the  left  of  the  worm  gear  is  a  bevel  gear  driving  the 


.         -  „ 

' 


FIG.  49 

spindle  D  of  the  governor,  and  at  the  right  an  eccen- 
tric which  gives  a  vibratory  motion  to  the  lever  F. 
The  crank  C  upon  the  end  of  the  shaft  operates  the 
oil  pump.  The  speed  of  the  turbine  is  controlled  by 
admitting  the  steam  in  puffs  of  greater  or  less  dura- 
tion according  to  the  load.  The  lever  F,  having  its 
fulcrum  in  the  collar  surrounding  the  shaft,  operates 
with  each  vibration  of  the  eccentric  the  pilot  valve. 
The  valve  is  explained  in  detail  later. 


WESTINGHOUSE-PARSONS  TURBINE 


8l 


This  form  of  governor  has  been  superseded  by  an 
improved  type,  but  so  many  have  been  made  that  it 
will  be  well  to  describe  its  construction  and  adjust- 


no.  50 


82  STEAM  TURBINES 

ment.  The  two  balls  W  W  (Fig.  50)  are  mounted 
on  the  ends  of  bell  cranks  N,  which  rest  on  knife  edges. 
The  other  end  of  the  bell  cranks  carry  rollers  upon 
which  rest  a  plate  P,  which  serves  as  a  support  for 
the  governor  spring  S.  They  are  also  attached  by 
links  to  a  yoke  and  sleeve  E  which  acts  as  a  fulcrum 
for  the  lever  F.  The  governor  is  regulated  by  means 
of  the  spring  S  resting  on  the  plate  P  and  compressed 
by  a  large  nut  G  on  the  upper  end  of  the  governor 
spindle,  which  nut  turns  on  a  threaded  quill  /,  held 
in  place  by  the  nut  H  on  the  end  of  the  governor 
spindle  and  is  held  tight  by  the  lock-nut  K.  To 
change  the  compression  of  the  spring  and  thereby  the 
speed  of  the  turbine  the  lock-nut  must  first  be  loos- 
ened and  the  hand-nut  raised  to  lower  the  speed  or 
lowered  to  raise  the  speed  as  the  case  may  be.  This 
operation  may  be  accomplished  while  the  machine 
is  either  running  or  at  rest. 

The  plate  P  rests  upon  ball  bearings  so  that  by 
simply  bringing  pressure  to  bear  upon  the  hand-wheel, 
which  is  a  part  of  the  quill  /,  the  spring  and  lock-nut 
may  be  held  at  rest  and  adjusted  while  the  rest  of 
the  turbine  remains  unaffected.  Another  lever  is 
mounted  upon  the  yoke  E  on  the  pin  shown  at  I ,  the 
other  end  of  which  is  fastened  to  the  piston  of  a  dash- 
pot  so  as  to  dampen  the  governor  against  vibration. 
Under  the  yoke  E  will  be  noticed  a  small  trigger  M 
which  is  used  to  hold  the  governor  in  the  full-load 
position  when  the  turbine  is  at  rest. 

The  throwing  out  of  the  weights  elevates  the  sleeve 
E.  carrying  with  it  the  collar  C,  which  is  spanned  by 


WESTINGHOUSE-PARSONS  TURBINE  83 

the  lever  F  upon  the  shaft  H.  The  later  turbines  are 
provided  with  an  improved  form  of  governor  operating 
on  the  same  principle,  but  embodying  several  impor- 
tant features.  First,  the  spindle  sleeve  is  integral 
with  the  governor  yoke,  and  the  whole  rotates  about 
a  vertical  stationary  spindle,  so  that  two  motions  are 
encountered  —  a  rotary  motion  and  an  up  and  down 
motion,  according  to  the  position  taken  by  the  gov- 
ernor. This  spiral  motion  almost  entirely  eliminates 
the  effect  of  friction  of  rest,  and  thereby  enhances  the 
sensitiveness  of  the  governor.  Second,  the  governor 
weights  move  outward  on  a  parallel  motion  opposed 
directly  by  spring  thrust,  thus  relieving  the  fulcrum 
entirely  of  spring  thrust.  Third,  the  lay  shaft  driving 
the  governor  oil  pump  and  reciprocator  is  located 
underneath  the  main  turbine  shaft,  so  that  the  rotor 
may  be  readily  removed  without  in  the  least  disturb- 
ing the  governor  adjustment. 

THE  VALVE-GEAR 

The  valve-gear  is  shown  in  section  in  Fig.  51,  the 
main  admission  being  shown  at  V^  at  the  right,  and 
the  secondary  K2  at  the  left  of  the  steam  inlet.  The 
pilot  valve  F  receives  a  constant  reciprocating  motion 
from  the  eccentric  upon  the  layshaft  of  the  turbine 
through  the  lever  F  (Fig.  50).  These  reciprocations 
run  from  150  to  180  per  minute.  The  space  beneath 
the  piston  C  is  in  communication  with  the  large  steam 
chest,  where  exists  the  initial  pressure  through  the 
port  A;  the  admission  of  steam  to  the  piston  C  being 


84  STEAM  TURBINES 

controlled  by  a  needle  valve  B.  The  pilot  valve 
connects  the  port  E,  leading  from  the  space  beneath 
the  piston  to  an  exhaust  port  /. 

When  the  pilot  valve  is  closed,  the  pressures  can 
accumulate  beneath  the  piston  C  and  raise  the  main 
admission  valve  from  its  seat.  When  the  pilot  valve 
opens,  the  pressure  beneath  the  piston  is  relieved  and 
it  is  seated  by  the  helical  spring  above.  If  the  ful- 
crum E  (Fig.  50)  of  the  lever  F  were  fixed  the  admis- 
sion would  be  of  an  equal  and  fixed  duration.  But 
if  the  governor  raises  the  fulcrum  E,  the  pilot  valve 
F  (Fig.  51)  will  be  lowered,  changing  the  relations 
of  the  openings  with  the  working  edges  of  the  ports. 

The  seating  of  the  main  admission  valve  is  cush- 
ioned by  the  dashpot,  the  piston  of  which  is  shown 
in  section  at  G  (Fig.  51).  The  valve  may  be  opened 
by  hand  by  means  of  the  lever  K,  to  see  if  it  is  per- 
fectly free. 

The  secondary  valve  is  somewhat  different  in  its 
action.  Steam  is  admitted  to  both  sides  of  its  actu- 
ating piston  through  the  needle  valves  M  M,  and  the 
chamber  from  which  this  steam  is  taken  is  connected 
with  the  under  side  of  the  main  admission  valve,  so 
that  no  steam  can  reach  the  actuating  piston  of  the 
secondary  valve  until  it  has  passed  through  the  pri- 
mary valve.  When  the  pilot  valve  is  closed,  the 
pressures  equalize  above  and  below  the  piston  N  and 
the  valve  remains  upon  its  seat.  When  the  load 
upon  the  turbine  exceeds  its  rated  capacity,  the  pilot 
valve  moves  upward  so  as  to  connect  the  space  above 
the  piston  with  the  exhaust  L,  relieving  the  pressure 


WESTINGHOUSE-PARSONS  TURBINE  85 

upon  the  upper  side  and  allowing  the  greater  pressure 
below  to  force  the  valve  open,  which  admits  steam 
to  the  secondary  stage  of  the  turbine. 


86  STEAM  TURBINES 

It  would  do  no  good  to  admit  more,  steam  to  the 
first  stage,  for  at  the  rated  capacity  that  stage  is 
taking  all  the  steam  for  which  the  blade  area  will 
afford  a  passage.  The  port  connecting  the  upper 
side  of  the  piston  N  with  the  exhaust  may  be  per- 
manently closed  by  means  of  the  hand  valve  Q,  to 
be  found  on  the  side  of  the  secondary  pilot  valve 
chest,  thus  cutting  the  secondary  valve  entirely  out 
of  action.  No  dashpot  is  necessary  on  this  valve, 
the  compression  of  the  steam  in  the  chamber  W  by 
the  fall  of  the  piston  being  sufficient  to  avoid  shock. 

The  timing  of  the  secondary  valve  is  adjusted  by 
raising  or  lowering  the  pilot  valve  by  means  of  the 
adjustment  provided.  It  should  open  soon  enough 
so  that  there  will  not  be  an  appreciable  drop  in  speed 
before  the  valve  comes  into  play.  The  economy  of 
the  machine  will  be  impaired  if  the  valve  is  allowed 
to  open  too  soon. 

SAFETY  STOP  GOVERNOR 

This  device  is  mounted  on  the  governor  end  of  the  tur- 
bine shaft,  as  shown  in  Figs.  52  and  53.  When  the  speed 
reaches  a  predetermined  limit,  the  plunger  A,  having 
its  center  of  gravity  slightly  displaced  from  the  center 
of  rotation  of  the  shaft,  is  thrown  radially  outward 
and  strikes  the  lever  B.  It  will  easily  be  understood 
that  when  the  plunger  starts  outward,  the  resistance 
of  spring  C  is  rapidly  overcome,  since  the  centrifugal 
force  increases  as  the  square  of  the  radius,  or  in  this 
case  the  eccentricity  of  the  center  of  gravity  relative 
to  the  center  of  rotation.  Hence,  the  lever  is  struck 


WESTINGHOUSE-PARSONS  TURBINE 


a  sharp  blow.  This  releases  the  trip  E  on  the  outside 
of  the  governor  casing,  and  so  opens  the  steam  valve 
F,  which  releases  steam  from  beneath  the  actuating 
piston  of  a  quick-closing  throttle  valve,  located  in  the 
steam  line.  Thus,  within  a  period  of  usually  less  than 
one  second,  the  steam  is  entirely  shut  off  from  the 
turbine  when  the  speed  has  exceeded  7  or  8  per  cent 
of  the  normal. 


FIG.    52 

THE  OILING  SYSTEM 

Mounted  on  the  end  of  the  bedplate  is  the  oil  pump, 
operated  from  the  main  shaft  of  the  turbine  as  pre- 
viously stated.  This  may  be  of  the  plunger  type 
shown  in  Fig.  54,  or  upon  the  latest  turbine,  the 
rotary  type  shown  in  Fig.  55.  Around  the  bedplate 
are  located  the  oil-cooling  coils,  the  oil  strainer,  the 
oil  reservoir  and  the  oil  pipings  to  the  bearing. 


STEAM  TURBINES 


The  oil  reservoir,  cooler,  and  piping  are  all  outside 
the  machine  and  easily  accessible  for  cleaning.  Usually 
a  corrugated-steel  floor  plate  covers  all  this  apparatus, 


so  that  it  will  not  be  unsightly  and  accumulate  dirt, 
particularly  when  the  turbine  is  installed,  so  that  all 
this  apparatus  is  below  the  floor  level;  i.e.,  when  the 
top  of  the  bedplate  comes  flush  with  the  floor  line. 


WESTINGHOUSE-PARSONS  TURBINE 


89 


In  cases  where  the  turbine  is  set  higher,  a  casing  is 
usually  built  around  this  material  so  that  it  can  be  easily 
removed,  and  forms  a  platform  alongside  the  machine. 


FIG.  54 

The  oil  cooler,  shown  in  Fig.  56,  is  of  the  counter- 
current  type,  the  water  entering  at  A  and  leaving  at 
B,  oil  entering  at  C  (opening  not  shown)  and  leaving 
at  D.  The  coils  are  of  seamless  drawn  copper,  and  at- 
tached to  the  cover  by  coupling  the  nut.  The  water 
manifold  F  is  divided  into  compartments  by  trans- 


STEAM  TURBINES 


WESTINGHO USE-PARSONS  TURBINE  91 


92 


STEAM   TURBINES 


verse  ribs,  each  compartment  connecting  the  inlet  of 
each  coil  with  the  outlet  of  the  preceding  coil,  thus 
placing  all  coils  in  series.  These  coils  are  removable 
in  one  piece  with  the  coverplate  without  disturbing 
the  rest  of  the  oil  piping. 

BLADING 

The  blades  are  drawn  from  a  rod  consisting  of  a 
steel  core  coated  with  copper  so  intimately  connected 
with  the  other  metal  that  when  the  bar  is  drawn  to 


FIG.  57 

the  section  required  for  the  blading,  the  exterior 
coating  drawn  with  the  rest  of  the  bar  forms  a 
covering  of  uniform  thickness  as  shown  in  Fig.  57. 
The  bar  after  being  drawn  through  the  correct 
section  is  cut  into  suitable  lengths  punched  as  at  A 
(Fig.  58),  near  the  top  of  the  blade,  and  has  a  groove 
shown  at  B  (Fig.  59),  near  the  root,  stamped  in 
its  concave  face,  while  the  blade  is  being  cut  to  length 
and  punched.  The  blades  are  then  set  into  grooves 


WESTINGHOUSE-P ARSONS  TURBINE 


93 


cut  into  the  rotor  drum  or  the  concave  surface  of  the 
casing,  and  spacing  or  packing  pieces  C  (Fig.  59) 
placed  between  them.  These  spacing  pieces  are  of 
soft  iron  and  of  the  form  which  is  desired  that  the 
passage  between  the  blades  shall  take.  The  groove 
made  upon  the  inner  face  of  .the  blade  is  sufficiently 
near  to  the  root  to  be  covered  by  this  spacing  piece. 
When  the  groove  has  been  filled  the  soft-iron  pieces 


BLADE  PUNCHED      BLADE  LASHED 

FIG.    58 


are  calked  or  spread  so  as  to  hold  the  blades  firmly 
in  place.  A  wire  of  comma  section,  as  shown  at  A 
(Fig.  59),  is  then  strung  through  the  punches  near 
the  outer  ends  of  the  blades  and  upset  or  turned 
over  as  shown  at  the  right  in  Fig.  58.  This  up- 
setting is  done  by  a  tool  which  shears  the  tail  of  the 
comma  at  the  proper  width  between  the  blades.  The 


94 


STEAM   TURBINES 


bent-down  portion  on  either  side  of  the  blade  holds 
it  rigidly  in  position  and  the  portion  retained  within 
the  width  of  the  blade  would  retain  the  blade  in  its 


WESTINGHOUSE-PARSONS  TURBINE  95 

radial  position  should  it  become  loosened  or  broken 
off  at  the  root.  This  comma  lashing,  as  it  is  called, 
takes  up  a  small  proportion  only  of  the  blade  length 
or  projection  and  makes  a  job  which  is  surprisingly 
stiff  and  rigid,  and  yet  which  yields  in  case  of  serious 
disturbance  rather  than  to  maintain  a  contact  which 
would  result  in  its  own  fusing  or  the  destruction  of 
some  more  important  member. 

STARTING  UP  THE  TURBINE 

When  starting  up  the  turbine  for  the  first  time,  or 
after  any  extended  period  of  idleness,  special  care 
must  be  taken  to  see  that  everything  is  in  good  condi- 
tion and  that  all  parts  of  the  machine  are  clean  and 
free  from  injury.  The  oil  piping  should  be  thoroughly 
inspected  and  cleaned  out  if  there  is  any  accumula- 
tion of  dirt.  The  oil  reservoirs  must  be  very  carefully 
wiped  out  and  minutely  examined  for  the  presence 
of  any  grit.  (Avoid  using  cotton  waste  for  this,  as 
a  considerable  quantity  of  lint  is  almost  sure  to  be 
left  behind  and  this  will  clog  up  the  oil  passages  in 
the  bearings  and  strainer.) 

The  pilot  valves  should  be  removed  from  the  barrel 
and  wiped  off,  and  the  barrels  themselves  cleaned  out 
by  pushing  a  soft  cloth  through  them  with  a  piece  of 
wood.  In  no  case  should  any  metal  be  used. 

If  the  turbine  has  been  in  a  place  where  there  was 
dirt  or  where  there  has  been  much  dust  blowing  around, 
the  bearings  should  be  removed  from  the  spindle  and 
taken  apart  and  thoroughly  cleaned.  With  care  this 
can  be  done  without  removing  the  spindle  from  the 


96  STEAM  TURBINES 

cylinder,  by  taking  off  the  bearing  covers  and  very 
carefully  lifting  the  weight  of  the  spindle  off  the  bear- 
ings, then  sliding  back  the  bearings.  It  is  best  to 
lift  the  spindle  by  means  of  jacks  and  a  rope  sling,  as, 
if  a  crane  is  used,  there  is  great  danger  of  lifting  the 
spindle  too  high  and  thereby  straining  it  or  injuring 
the  blades.  After  all  the  parts  have  been  carefully 
gone  over  and  cleaned,  the  oil  for  the  bearing  lubrica- 
tion should  be  put  into  the  reservoirs  by  pouring  it 
into  the  governor  gear  case  G  (Fig.  34).  Enough  oil 
should  be  put  in  so  that  when  the  governor,  gear  case, 
and  all  the  bearing-supply  pipes  are  full,  the  supply 
to  the  oil  pump  is  well  covered. 

Special  care  should  be  taken  so  that  no  grit  gets 
into  the  oil  when  pouring  it  into  the  machine.  Con- 
siderable trouble  may  be  saved  in  this  respect  by 
pouring  the  oil  through  cloth. 

A  very  careful  inspection  of  the  steam  piping  is 
necessary  before  the  turbine  is  run.  If  possible  it 
should  be  blown  out  by  steam  from  the  boilers  before 
it  is  finally  connected  to  the  turbine.  Considerable 
annoyance  may  result  by  neglecting  this  precaution, 
from  particles  of  scale,  red  lead,  gasket,  etc.,  out  of  the 
steam  pipe,  closing  up  the  passages  of  the  guide  blades. 

When  starting  up,  always  begin  to  revolve  the 
spindle  without  vacuum  being  on  the  turbine.  After 
the  spindle  is  turning  slowly,  bring  the  vacuum  up. 
The  reason  for  this  is,  that  when  the  turbine  is  stand- 
ing still,  the  glands  do  not  pack  and  air  in  consider- 
able quantity  will  rush  through  the  glands  and  down 
through  the  exhaust  pipe.  This  sometimes  has  the 


WESTINGHOUSE-PARSONS  TURBINE  97 

effect  of  unequal  cooling.  In  case  the  turbine  'is  used 
in  conjunction  with  its  own  separate  condenser,  the 
circulating  pump  may  be  started  up,  then  the  turbine 
revolved,  and  afterward  the  air  pump  put  in  opera- 
tion; then,  last,  put  the  turbine  up  to  speed.  In 
cases,  however,  where  the  turbine  exhausts  into  the 
same  condenser  with  other  machinery  and  the  con- 
denser is  therefore  already  in  operation,  the  valve 
between  the  turbine  and  the  condenser  system  should 
be  kept  closed  until  after  the  turbine  is  revolved,  the 
turbine  in  the  meantime  exhausting  through  the 
relief  valve  to  atmosphere. 

Care  must  always  be  taken  to  see  that  the  turbine 
is  properly  warmed  up  before  being  caused  to  revolve, 
but  in  cases  where  high  superheat  is  employed  always 
revolve  the  turbine  just  as  soon  as  it  is  moderately 
hot,  and  before  it  has  time  to  become  exposed  to 
superheat. 

In  the  case  of  highly  superheated  steam,  it  is  not 
undesirable  to  provide  a  connection  in  the  steam  line 
by  means  of  which  the  turbine  may  be  started  up  with 
saturated  steam  and  the  superheat  gradually  applied 
after  the  shaft  has  been  permitted  to  revolve. 

For  warming  up,  it  is  usual  practice  to  set  the  gov- 
ernor on  the  trigger  (see  Fig.  50)  and  open  the  throttle 
valve  to  allow  the  entrance  of  a  small  amount  of 
steam. 

It  is  always  well  to  let  the  turbine  operate  at  a  re- 
duced speed  for  a  time,  until  there  is  assurance  that 
the  condenser  and  auxiliaries  are  in  proper  working 
order,  that  the  oil  pump  is  working  properly,  and 


98  STEAM  TURBINES 

that  there  is  no  sticking  in  the  governor  or  the  valve 
gear. 

After  the  turbine  is  up  to  speed  and  on  the  governor, 
it  is  well  to  count  the  speed  by  counting  the  strokes 
of  the  pump  rod,  as  it  is  possible  that  the  adjustment 
of  the  governor  may  have  become  changed  while  the 
machine  has  been  idle.  It  is  well  at  this  time,  while 
there  is  no  load  on  the  turbine,  to  be  sure  that  the 
governor  controls  the  machine  with  the  throttle  wide 
open.  It  might  be  that  the  main  poppet  valve  has 
sustained  some  injury  not  evident  on  inspection,  or 
was  leaking  badly.  Should  there  be  some  such  de- 
fect, steps  should  be  taken  to  regrind  the  valve  to  its 
seat  at  the  first  opportunity. 

On  the  larger  machines  an  auxiliary  oil  pump  is 
always  furnished.  This  should  be  used  before  start- 
ing up,  so  as  to  establish  the  oil  circulation  before 
the  turbine  is  revolved.  After  the  turbine  has  reached 
speed,  and  the  main  oil  pump  is  found  to  be  working 
properly,  it  should  be  possible  to  take  this  pump  out 
of  service,  and  start  it  again  only  when  the  turbine 
is  about  to  be  shut  down. 

If  possible,  the  load  should  be  thrown  on  gradually 
to  obviate  a  sudden,  heavy  demand  upon  the  boiler, 
with  its  sometimes  attendant  priming  and  rush  of 
water  into  the  steam  pipe,  which  is  very  apt  to  take 
place  if  the  load  is  thrown  on  too  suddenly.  A  slug 
of  water  will  have  the  effect  of  slowing  down  the 
turbine  to  a  considerable  extent,  causing  some  annoy- 
ance. There  is  not  likely  to  be  the  danger  of  the  dam- 
age that  is  almost  sure  to  occur  in  the  reciprocating 


WESTINGHOUSE-PARSONS  TURBINE  99 

engine,  but  at  the  same  time  it  is  well  to  avoid  this 
as  much  as  possible.  A  slug  of  water  is  obviously 
more  dangerous  when  superheated  steam  is  being  em- 
ployed, owing  to  the  extreme  temperature  changes 
possible. 

RUNNING 

While  the  turbine  is  running,  it  should  have  a  cer- 
tain amount  of  careful  attention.  This,  of  course, 
does  not  mean  that  the  engineer  must  stand  over  it 
every  minute  of  the  day,  but  he  must  frequently  in- 
spect such  parts  as  the  lubricators,  the  oiling  system, 
the  water  supply  to  the  glands  and  the  oil-cooling 
coil,  the  pilot  valve,  etc.  He  must  see  that  the  oil 
is  up  in  the  reservoir  and  showing  in  the  gage  glass 
provided  for  that  purpose,  and  that  the  oil  is  flowing 
freely  through  the  bearings,  by  opening  the  pet  cocks 
in  the  top  of  the  bearing  covers.  An  ample  supply  of 
oil  should  always  be  in  the  machine  to  keep  the  suc- 
tion in  the  tank  covered. 

Care  must  be  taken  that  the  pump  does  not  draw 
too  much  air.  This  can  usually  be  discovered  by  the 
bubbling  up  of  the  air  in  the  governor  case,  when 
more  oil  should  be  added. 

It  is  well  to  note  from  time  to  time  the  temperature 
of  the  bearings,  but  no  alarm  need  be  occasioned 
because  they  feel  warm  to  the  touch;  in  fact,  a  bearing 
is  all  right  as  long  as  the  hand  can  be  borne  upon  it 
even  momentarily.  The  oil  coming  from  the  bearings 
should  be  preferably  about  120  degrees  Fahrenheit 
and  never  exceed  160  degrees. 


100  STEAM  TURBINES 

It  should  generally  be  seen  that  the  oil-cooling  coil 
is  effective  in  keeping  the  oil  cool.  Sometimes  the 
cooling  water  deposits  mud  on  the  cooling  surface,  as 
well  as  the  oil  depositing  a  vaseline-like  substance, 
which  interferes  with  the  cooling  effect.  The  bearing 
may  become  unduly  heated  because  of  this,  when  the 
coil  should  be  taken  out  at  the  first  opportunity  and 
cleaned  on  the  outside  and  blown  out  by  steam  on  the 
inside,  if  this  latter  is  possible.  If  this  does  not 
reduce  the  temperature,  either  the  oil  has  been  in  use 
too  long  without  being  filtered,  or  the  quality  of  the 
oil  is  not  good. 

Should  a  bearing  give  trouble,  the  first  symptom 
will  be  burning  oil  which  will  smoke  and  give  off  dense 
white  fumes  which  can  be  very  readily  seen  and 
smelled.  However,  trouble  with  the  bearings  is  one 
of  the  most  unlikely  things  to  be  encountered,  and, 
if  it  occurs,  it  is  due  to  some  radical  cause,  such  as 
the  bearings  being  pinched  by  their  caps,  or  grit  and 
foreign  matter  being  allowed  to  get  into  the  oil. 

If  a  bearing  gets  hot,  be  assured  that  there  is  some 
very  radical  cause  for  it  which  should  be  immediately 
discovered  and  removed.  Never,  under  any  circum- 
stances, imagine  that  you  can  nurse  a  bearing,  that 
has  heated,  into  good  behavior.  Turbine  bearings 
are  either  all  right  or  all  wrong.  There  are  no  half- 
way measures. 

The  oil  strainer  should  also  be  occasionally  taken 
apart  and  thoroughly  cleaned,  which  operation  may 
be  performed,  if  necessary,  while  the  turbine  is  in 
operation.  The  screens  should  be  cleaned  by  being 


WESTINGHOUSE-PARSONS  TURBINE  101 

removed  from  their  case  and  thoroughly  blown  out 
with  steam.  In  the  case  of  a  new  machine,  this  may 
have  to  be  done  every  two  or  three  hours.  In  course 
of  time,  this  need  only  be  repeated  perhaps  once  a 
week.  The  amount  of  dirt  found  will  be  an  indica- 
tion of  the  frequency  with  which  this  cleaning  is 
necessary. 

The  proper  water  pressure,  about  five  pounds  per 
square  inch,  must  be  maintained  at  the  glands.  Any 
failure  of  this  will  mean  that  there  is  some  big  leak  in 
the  piping,  or  that  the  water  is  not  flowing  properly. 

The  pilot  valve  must  be  working  freely,  causing 
but  little  kick  on  the  governor,  and  should  be  lubri- 
cated from  time  to  time  with  good  oil. 

Should  it  become  necessary,  while  operating,  to 
shut  down  the  condenser  and  change  over  to  non- 
condensing  operation,  particular  care  should  be  ob- 
served that  the  change  is  not  made  too  suddenly  to 
non-condensing,  as  all  the  low-pressure  sections  of  the 
turbine  must  be  raised  to  a  much  higher  tempera- 
ture. While  this  may  not  cause  an  accident,  it  is 
well  to  avoid  the  stresses  which  necessarily  result 
from  the  sudden  change  of  temperature.  The  same 
reasons,  of  course,  do  not  hold  good  in  changing  from 
non-condensing  to  condensing. 

SHUTTING  DOWN 

When  shutting  down  the  turbine  the  load  may  be 
taken  off  before  closing  the  throttle;  or,  as  in  the  case 
of  a  generator  operating  on  an  independent  load,  the 
throttle  may  be  closed  first,  allowing  the  load  to  act 


102  STEAM  TURBINES 

as  a  brake,  bringing  the  turbine  to  rest  quickly.  In 
most  cases,  however,  the  former  method  will  have 
to  be  used,  as  the  turbine  generally  will  have  been 
operating  in  parallel  with  one  or  more  other  genera- 
tors. When  this  is  the  case,  partially  close  the  throttle 
just  before  the  load  is  to  be  thrown  off,  and  if  the  tur- 
bine is  to  run  without  load  for  some  time,  shut  off 
the  steam  almost  entirely  in  order  to  prevent  any 
chance  of  the  turbine  running  away.  There  is  no 
danger  of  this  unless  the  main  valve  has  been  dam- 
aged by  the  water  when  wet  steam  has  been  used,  or 
held  open  by  some  foreign  substance,  when,  in  either 
case,  there  may  be  sufficient  leakage  to  run  the  tur- 
bine above  speed,  while  running  light.  At  the  same 
time,  danger  is  well  guarded  against  by  the  auto- 
matic stop  valve,  but  it  is  always  well  to  avoid  a  pos- 
sible danger.  As  soon  as  the  throttle  is  shut,  stop 
the  condenser,  or,  in  the  case  where  one  condenser 
is  used  for  two  or  more  turbines,  close  the  valve  be- 
tween the  turbine  and  the  condenser.  Also  open  the 
drains  from  the  steam  strainer,  etc.  This  will  con- 
siderably reduce  the  time  the  turbine  requires  to  come 
to  rest.  Still  more  time  may  be  saved  by  leaving  the 
field  current  on  the  generator. 

Care  should  be  taken,  when  the  vacuum  falls  and 
the  turbine  slows  down,  to  see  that  the  water  is  shut 
off  from  the  glands  for  fear  it  may  leak  out  to  such  an 
extent  as  to  let  the  water  into  the  bearings  and  im- 
pair the  lubricating  qualities  of  the  oil. 


WESTINGHOUSE-PARSONS  TURBINE          103 

INSPECTION 

At  regular  intervals  thorough  inspection  should  be 
made  of  all  parts  of  the  turbine.  As  often  as  it 
appears  necessary  from  the  temperature  of  the  oil, 
depending  on  the  quality  of  the  oil  and  the  use  of  the 
turbine,  remove  the  oil-cooling  coil  and  clean  it  both 
on  the  inside  and  outside  as  previously  directed;  also 
clean  out  the  chamber  in  which  it  is  kept.  Put  in  a 
fresh  supply  of  oil.  This  need  not  necessarily  be  new, 
but  may  be  oil  that  has  been  in  use  before  but  has 
been  filtered.  We  recommend  that  an  oil  filter  be 
kept  for  this  purpose.  Entirely  new  oil  need  only 
be  put  into  the  turbine  when  the  old  oil  shows  marked 
deterioration.  With  a  first-class  oil  this  will  prob- 
ably be  a  very  infrequent  necessity,  as  some  new  oil 
has  to  be  put  in  from  time  to  time  to  make  up  the 
losses  from  leakage  and  waste. 

Clean  out  the  oil  strainer,  blowing  steam  through 
the  wire  gauze  to  remove  any  accumulation  of  dirt. 
Every  six  months  to  a  year  take  off  the  bearing  covers, 
remove  the  bearings,  and  take  them  apart  and  clean 
out  thoroughly.  Even  the  best  oil  will  deposit  more 
or  less  solid  matter  upon  hot  surfaces  in  time,  which 
will  tend  to  prevent  the  free  circulation  of  the  oil 
through  the  bearings  and  effectively  stop  the  cushion- 
ing effect  on  the  bearings.  Take  apart  the  main  and 
secondary  valves  and  clean  thoroughly,  seeing  that  all 
parts  are  in  good  working  order.  Clean  and  inspect 
the  governor  and  the  valve-gear,  wiping  out  any  accu- 
mulation of  oil  and  dirt  that  may  appear.  Be  sure  to 


104  STEAM  TURBINES 

clean  out  the  drains  from  the  glands  so  that  any  water 
that  may  pass  out  of  them  will  run  off  freely  and  will 
not  get  into  the  bearings. 

At  the  end  of  the  first  three  months,  and  after  that 
about  once  a  year,  take  off  the  cylinder  cover  and 
remove  the  spindle.  When  the  turbine  is  first  started 
up,  there  is  very  apt  to  be  considerable  foreign  matter 
come  over  in  the  steam,  such  as  balls  of  red  lead  or 
small  pieces  of  gasket  too  small  to  be  stopped  by  the 
strainer.  These  get  into  the  guide  blades  in  the  cylin- 
der and  quite  effectively  stop  them  up.  Therefore, 
the  blades  should  be  gone  over  very  carefully,  and 
any  such  additional  accumulation  removed.  Exam- 
ine the  glands  and  equilibrium  ports  for  any  dirt  or 
broken  parts.  Particularly  examine  the  glands  for 
any  deposit  of  scale.  All  the  scale  should  be  chipped 
off  the  gland  parts,  as,  besides  preventing  the  glands 
from  properly  packing,  this  accumulation  will  cause 
mechanical  contact  and  perhaps  cause  vibration  of  the 
machine  due  to  lack  of  freedom  of  the  parts.  The 
amount  of  scale  found  after  the  first  few  inspections 
will  be  an  indication  of  how  frequently  the  cleaning 
should  be  done.  As  is  discussed  later,  any  water 
that  is  unsuitable  for  boiler  feed  should  not  be  used 
in  the  glands. 

In  reassembling  the  spindle  and  cover,  very  great' 
care  must  be  taken  that  no  blades  are  damaged  and 
that  nothing  gets  into  the  blades.  Nearly  all  the 
damage  that  has  been  done  to  blades  has  resulted 
from  carelessness  in  this  respect;  in  fact,  it  is  impos- 
sible to  be  too  careful.  Particular  care  is  also  to  be 


WESTINGHOUSE-PARSONS  TURBINE  105 

taken  in  assembling  all  the  parts  and  in  handling 
them,  as  slight  injury  may  cause  serious  trouble.  In 
no  case  should  a  damaged  part  be  put  back  until  the 
injury  has  been  repaired. 

If  for  any  reason  damaged  blades  cannot  be  repaired 
at  the  time,  they  can  be  easily  removed  and  the 
turbine  run  again  without  them  until  it  is  convenient 
to  put  in  new  ones;  in  fact,  machines  have  been  run 
at  full  load  with  only  three-quarters  of  the  total  num- 
ber of  blades.  In  such  an  event  remove  the  corre- 
sponding stationary  blades  as  well  as  the  moving 
blades,  so  as  not  to  disturb  the  balance  of  the  end 
thrust. 

CONDITIONS  CONDUCIVE  TO  SUCCESSFUL  OPERATION 

In  the  operation  of  the  turbine  and  the  conditions 
of  the  steam,  both  live  and  exhaust  play  a  very 
important  part.  It  has  been  found  by  expensive 
experimenting  that  moisture  in  the  steam  has  a  very 
decided  effect  on  the  economy  of  operation ;  or  consid- 
erably more  so  than  in  the  case  of  the  reciprocating 
engine.  In  the  latter  engine,  2  per  cent,  of  moisture 
will  mean  very  close  to  2  per  cent,  increase  in  the 
amount  of  water  supplied  to  the  engine  for  a  given 
power.  On  the  other  hand,  in  the  turbine  2  per  cent, 
moisture  will  cause  an  addition  of  more  nearly  4  per 
cent.  It  is  therefore  readily  seen  that  the  drier  the 
entering  steam,  the  better  will  be  the  appearance  of 
the  coal  bill. 

By  judicious  use  of  first-class  separators  in  connec- 
tion with  a  suitable  draining  system,  such  as  the 


lo6  STEAM  TURBINES 

Holly  system  which  returns  the  moisture  separated 
from  the  steam,  back  to  the  boilers,  a  high  degree 
of  quality  may  be  obtained  at  the  turbine  with  prac- 
tically no  extra  expense  during  operation.  Frequent 
attention  should  be  given  the  separators  and  traps 
to  insure  their  proper  operation.  The  quality  of  the 
steam  may  be  determined  from  time  to  time  by  the 
use  of  a  throttling  calorimeter.  Dry  steam,  to  a  great 
extent,  depends  upon  the  good  and  judicious  design 
of  steam  piping. 

Superheated  steam  is  of  great  value  where  it  can  be 
produced  economically,  as  even  a  slight  degree  in- 
sures the  benefits  to  be  derived  from  the  use  of  dry 
steam.  The  higher  superheats  have  been  found  to 
increase  the  economy  to  a  considerable  extent. 

When  superheat  of  a  high  degree  (100  degrees 
Fahreneheit  or  above)  is  used  special  care  must  be 
exercised  to  prevent  a  sudden  rise  of  the  superheat 
of  any  amount.  The  greatest  source  of  trouble  in 
this  respect  is  when  a  sudden  demand  is  made  for  a 
large  increase  in  the  amount  of  steam  used  by  the  en- 
gine, as  when  the  turbine  is  started  up  and  the  super- 
heater has  been  in  operation  for  some  time  before, 
the  full  load  is  suddenly  thrown  on.  It  will  be  read- 
ily seen  that  with  the  turbine  running  light  and  the 
superheater  operating,  there  is  a  very  small  amount 
of  steam  passing  through;  in  fact,  practically  none, 
and  this  may  become  very  highly  heated  in  the  super- 
heater, but  loses  nearly  all  its  superheat  in  passing 
slowly  to  the  turbine;  then,  when  a  sudden  demand 
is  made,  this  very  high  temperature  steam  is  drawn 


WESTINGHOUSE-P ARSONS  TURBINE  107 

into  the  turbine.  This  may  usually  be  guarded  against 
where  a  separately  fired  superheater  is  used,  by  keep- 
ing the  fire  low  until  the  load  comes  on,  or,  in  the  case 
where  the  superheater  is  part  of  the  boiler,  by  either 
not  starting  up  the  superheater  until  after  load  comes 
on,  or  else  keeping  the  superheat  down  by  mixing 
saturated  steam  with  that  which  has  been  superheated. 
After  the  plant  has  been  started  up  there  is  little 
danger  from  this  source,  but  such  precautions  should 
be  taken  as  seem  best  in  the  particular  cases. 

Taking  up  the  exhaust  end  of  the  turbine,  we  have 
a  much  more  striking  departure  from  the  conditions 
familiar  in  the  reciprocating  engine.  Due  to  the 
limits  imposed  upon  the  volume  of  the  cylinder  of 
the  engine,  any  increase  in  the  vacuum  over  23  or 
24  inches,  in  the  case,  for  instance,  of  a  compound- 
condensing  engine,  has  very  little,  if  any,  effect  on 
the  economy  of  the  engine.  With  the  turbine,  on  the 
other  hand,  any  increase  of  vacuum,  even  up  to  the 
highest  limits,  increases  the  economy  to  a  very  con- 
siderable extent  and,  moreover,  the  higher  the  vacuum 
the  greater  will  be  the  increase  in  the  economy  for  a 
given  addition  to  the  vacuum.  Thus,  raising  the 
vacuum  from  27  to  28  inches  has  a  greater  effect 
than  from  23  to  24  inches.  For  this  reason  the 
engineer  will  readily  perceive  the  great  desirability  of 
maintaining  the  vacuum  at  the  highest  possible  point 
consistent  with  the  satisfactory  and  economical  op- 
eration of  the  condenser. 

The  exhaust  pipe  should  always  be  carried  down- 
ward to  the  condenser  when  possible,  to  keep  the 


lo8  STEAM  TURBINES 

water  from  backing  up  from  tfie  condenser  into  the 
turbine.  If  the  condenser  must  be  located  above 
the  turbine,  then  the  pipe  should  be  carried  first  down- 
ward and  then  upward  in  the  U  form,  in  the  manner 
of  the  familiar  "entrainer,"  which  will  be  found  effect- 
ively to  prevent  water  getting  back  when  the  turbine 

is  operating. 

CONDENSERS 

As  has  been  previously  pointed  out,  the  successful 
and  satisfactory  operation  of  the  turbine  depends 
very  largely  on  the  condenser.  With  the  recipro- 
cating engine,  if  the  condenser  will  give  25  inches 
vacuum,  it  is  considered  fairly  good,  and  it  is  allowed 
to  run  along  by  itself  until  the  vacuum  drops  to  some- 
where below  20  inches,  when  it  is  completely  gone 
over,  and  in  many  cases  practically  rebuilt  and  the 
vacuum  brought  back  to  the  original  25  inches.  It 
has  been  seen  that  this  sort  of  practice  will  never  do 
in  the  case  of  the  turbine  condenser  and,  unless  the 
vacuum  can  be  regularly  maintained  at  27  or  28  inches, 
the  condenser  is  not  doing  as  well  as  it  ought  to  do, 
or  it  is  not  of  the  proper  type,  unless  perhaps  the 
temperature  and  the  quantity  of  cooling  water  avail- 
able render  a  higher  vacuum  unattainable. 

On  account  of  the  great  purity  of  the  condensed 
steam  from  the  turbine  and  its  peculiar  availability 
for  boiler  feed  (there  being  no  oil  of  any  kind  mixed 
with  it  to  injure  the  boilers),  the  surface  condenser 
is  very  desirable  in  connection  with  the  turbine.  It 
further  recommends  itself  by  reason  of  the  high 
vacuum  obtainable. 


WESTINGHOUSE-P ARSONS   TURBINE 


109 


Where  a  condenser  system  capable  of  the  highest 
vacuum  is  installed,  the  need  of  utilizing  it  to  its 
utmost  capacity  can  hardly  be  emphasized  too  strongly. 
A  high  vacuum  will,  of  course,  mean  special  care  and 
attention,  and  continual  vigilance  for  air  leaks  in  the 
exhaust  piping,  which  will,  however,  be  fully  paid 
for  by  the  great  increase  in  economy. 

It  must  not  be  inferred  that  a  high  vacuum  is  essen- 
tial to  successful  operation  of  this  type  of  turbine, 
for  excellent  performance  both  in  the  matter  of  steam 
consumption  and  operation  is  obtained  with  inferior 
vacuum.  The  choice  of  a  condenser,  however,  is  a 
matter  of  special  engineering,  and  is  hardly  within  the 
province  of  this  article. 

OILS 

There  are  several  oils  on  the  market  that  are  suit- 
able for  the  purpose  of  the  turbine  oiling  system,  but 
great  care  must  be  exercised  in  their  selection.  In  the 
first  place,  the  oil  must  be  pure  mineral,  unadulter- 
ated with  either  animal  or  vegetable  oils,  and  must 
have  been  washed  free  from  acid.  Certain  brands 
of  oil  require  the  use  of  sulphuric  acid  in  their  manu- 
facture and  are  very  apt  to  contain  varying  degrees 
of  free  acid  in  the  finished  product.  A  sample  from 
one  lot  may  have  almost  no  acid,  while  that  from 
another  lot  may  contain  a  dangerous  amount. 

Mineral  oils  that  have  been  adulterated,  when 
heated  up,  will  partially  decompose,  forming  acid. 
These  oils  may  be  very  good  lubricants  when  first 
put  into  use,  but  after  awhile  they  lose  all  their  good 


I io  STEAM  TURBINES 

qualities  and  become  very  harmful  to  the  machine 
by  eating  the  journals  in  which  they  are  used.  These 
oils  must  be  very  carefully  avoided  in  the  turbine,  as 
the  cheapness  of  their  first  cost  will  in  no  way  pay 
for  the  damage  they  may  do.  A  very  good  and  simple 
way  to  test  for  such  adulterations  is  to  take  up  a 
quantity  of  the  oil  in  a  test  tube  with  a  solution  of 
borax  and  water.  If  there  is  any  animal  or  vegetable 
adulterant  present  it  will  appear  as  a  white  milk-like 
emulsion  which  will  separate  out  when  allowed  to 
stand.  The  pure  mineral  oil  will  appear  at  the  top 
as  a  clear  liquid  and  the  excess  of  the  borax  solution 
at  the  bottom,  the  emulsion  being  in  between.  A 
number  of  oils  also  contains  a  considerable  amount 
of  paraffin  which  is  deposited  in  the  oil-cooling  coil, 
preventing  the  oil  from  being  cooled  properly,  and  in 
the  pipes  and  bearings,  choking  the  oil  passages  and 
preventing  the  proper  circulation  of  the  oil  and  cush- 
ioning effect  in  the  bearing  tubes.  This  is  not  entirely 
a  prohibitive  drawback,  the  chief  objection  being 
that  it  necessitates  quite  frequently  cleaning  the 
cooling  coil,  and  the  oil  piping  and  bearings. 

Some  high-class  mineral  oils  of  high  viscosity  are 
inclined  to  emulsify  with  water,  which  emulsion  ap- 
pears as  a  jelly-like  substance.  It  might  be  added 
that  high-grade  oils  having  a  high  viscosity  might 
not  be  the  most  suitable  for  turbine  use. 

Since  the  consumption  of  oil  in  a  turbine  is  so  very 
small,  being  practically  due  only  to  leakage  or  spilling, 
the  price  paid  for  it  should  therefore  be  of  secondary 
importance,  the  prime  consideration  being  its  suitabil- 
ity for  the  purpose. 


WESTINGHOUSE-PARSONS  TURBINE  m 

In  some  cases  a  central  gravity  system  will  be  em- 
ployed, instead  of  the  oil  system  furnished  with  the 
turbine,  which,  of  course,'  will  be  a  special  considera- 
tion. 

For  large  installations  a  central  gravity  oiling  sys- 
tem has  much  to  recommend  it,  but  as  it  performs 
such  an  important  function  in  the  power  plant,  and 
its  failure  would  be  the  cause  of  so  much  damage, 
every  detail  in  connection  with  it  should  be  most 
carefully  thought  out,  and  designed  with  a  view  that 
under  no  combination  of  circumstances  would  it  be 
possible  for  the  system  to  become  inoperative.  One 
of  the  great  advantages  of  such  a  system  is  that  it 
can  be  designed  to  contain  very  large  quantities  of 
oil  in  the  settling  tanks;  thus  the  oil  will  have  quite 
a  long  rest  between  the  times  of  its  being  used  in  the 
turbine,  which  seems  to  be  very  helpful  in  extending 
the  life  of  the  oil.  Where  the  oil  can  have  a  long  rest 
for  settling,  an  inferior  grade  of  oil  may  be  used, 
providing,  however,  that  it  is  absolutely  free  of  acid. 


PROPER   METHOD   OF   TESTING   A   STEAM 
TURBINE1 

THE  condensing  arrangements  of  a  turbine  are 
perhaps  mainly  instrumental  in  determining  the 
method  of  test.  The  condensed  steam  alone,  issuing 
from  a  turbine  having,  for  example,  a  barometric  or 
jet  condenser,  cannot  be  directly  measured  or  weighed, 
unless  by  meter,  and  these  at  present  are  not  suffi- 
ciently accurate  to  warrant  their  use  for  test  purposes, 
if  anything  more  than  approximate  results  are  de- 
sired. The  steam  consumed  can,  in  such  a  case,  only 
be  arrived  at  by  measuring  the  amount  of  condensing 
water  (which  ultimately  mingles  with  the  condensed 
steam),  and  subtracting  this  quantity  from  the  con- 
denser's total  outflow.  Consequently,  in  the  case  of 
turbines  equipped  with  barometric  or  jet  condensers, 
it  is  often  thought  sufficient  to  rely  upon  the  measure- 
ment taken  of  the  boiler  feed,  and  the  boiler's  initial 
and  final  contents.  Turbines  equipped  with  surface- 
condensing  plants  offer  better  facilities  for  accurate 
steam-consumption  calculations  than  those  plants  in 
which  the  condensed  exhaust  steam  and  the  circulating 
water  come  into  actual  contact,  it  being  necessary 

1  Contributed  to  Power  by  Thomas  Franklin. 
112 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     113 

with  this  type  simply  to  pump  the  condensed  steam 
into  a  weighing  or  measuring  tank. 

In  the  case  of  a  single-flow  turbine  of  the  Parsons 
type,  the  covers  should  be  taken  off  and  every  row  of 
blades  carefully  examined  for  deposits,  mechanical 
irregularities,  deflection  from  the  true  radial  and  ver- 
tical positions,  etc.  The  blade  clearances  also  should 
be  gaged  all  around  the  circumference,  to  insure  this 
clearance  being  an  average  working  minimum.  On  no 
account  should  a  test  be  proceeded  with  when  any 
doubt  exists  as  to  the  clearance  dimensions. 


Fine  Clearance  here, 


FIG.   60 

The  dummy  rings  of  a  turbine,  namely,  those  rings 
which  prevent  excessive  leakage  past  the  balancing 
pistons  at  the  high-pressure  end,  should  have  especial 
attention  before  a  test.  A  diagrammatic  sketch  of 
a  turbine  cylinder  and  spindle  is  shown  in  Fig.  60,  for 
the  benefit  of  those  unfamiliar  with  the  subject.  In 
this  A  is  the  cylinder  or  casing,  B  the  spindle  or  rotor, 
and  C  the  blades.  The  balancing  pistons,  D,  E,  and 
F,  the  pressure  upon  which  counterbalances  the  axial 
thrust  upon  the  three-bladed  stages,  are  grooved,  the 
brass  dummy  rings  G  G  in  the  cylinder  being  alined 
within  a  few  thousandths  of  an  inch  of  the  grooved 


114  STEAM  TURBINES 

walls,  as  indicated.  After  these  rings  have  been 
turned  (the  turning  being  done  after  the  rings  have 
been  calked  in  the  cylinder),  it  is  necessary  to  insure 
that  each  ring  is  perfectly  bedded  to  its  respective 
grooved  wall  so  that  when  running  the  several  small 
clearances  between  the  groove  walls  and  rings  are 
equal.  A  capital  method  of  thus  bedding  the  dummy 
rings  is  to  grind  them  down  with  a  flour  of  emery  or 
carborundum,  while  the  turbine  spindle  is  slowly 
revolving  under  steam.  Under  these  conditions  the 
operation  is  performed  under  a  high  temperature,  and 
any  slight  permanent  warp  the  rings  may  take  is  thus 
accounted  for.  The  turbine  thrust-block,  which  main- 
tains the  spindle  in  correct  position  relatively  to  the 
spindle,  may  also  be  ground  with  advantage  in  a 
similar  manner. 

The  dummy  rings  are  shown  on  a  large  scale  in 
Fig.  61,  and  their  preliminary  inspection  may  be  made 
in  the  following  manner: 

The  spindle  has  been  set  and  the  dummy  rings  C 
are  consequently  within  a  few  thousandths  of  an  inch 
of  the  walls  d  of  the  spindle  dummy  grooves  D.  The 
clearances  allowed  can  be  gaged  by  a  feeler  placed 
between  a  ring  and  the  groove  wall.  Before  a  test  the 
spindle  should  be  turned  slowly  around,  the  feelers 
being  kept  in  position.  By  this  means  any  mechanical 
flaws  or  irregularities  in  the  groove  walls  may  be 
detected. 

It  has  sometimes  been  found  that  the  groove  walls, 
under  the  combined  action  of  superheated  steam  and 
friction,  in  cases  where  actual  running  contact  has 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     115 

occurred,  have  worn  very  considerably,  the  wear  tak- 
ing the  form  of  a  rapid  crumbling  away.  It  is  possible, 
however,  that  such  deterioration  may  be  due  solely  to 
the  quality  of  the  steel  from  which  the  spindle  is  forged. 
Good  low-percentage  carbon-annealed  steel  ought  to 
withstand  considerable  friction ;  at  all  events  the  wear 


FIG.    6 1 


under  any  conditions  should  be  uniform.  If  the  sur- 
faces of  both  rings  and  grooves  be  found  in  bad  con- 
dition, they  should  be  re-ground,  if  not  sufficiently 
worn  to  warrant  skimming  up  with  a  tool. 

As  the  question  of  dummy  leakage  is  of  very  con- 
siderable importance  during  a  test,  it  may  not  be  inad- 
visable to  describe  the  manner  of  setting  the  spindle 
and  cylinder  relatively  to  one  another  to  insure  mini- 
mum leakage,  and  the  methods  of  noting  their  conduct 


n6 


STEAM  TURBINES 


during  a  prolonged  run.  In  Fig.  62,  showing  the 
spindle,  B  is  the  thrust  (made  in  halves),  the  rings  0 
of  which  fit  into  the  grooved  thrust-rings  C  in  the 
spindle.  Two  lugs  D  are  cast  on  each  half  of  the 
thrust-block.  The  inside  faces  of  these  lugs  are  ma- 
chined, and  in  them  fit  the  ball  ends  of  the  levers  E, 
the  latter  being  fulcrumed  at  F  in  the  thrust-bearing 


FIG.   62 


cover.  The  screws  G,  working  in  bushes,  also  fit  into 
the  thrust-bearing  cover,  and  are  capable  of  pushing 
against  the  ends  of  the  levers  E  and  thus  adjusting  the 
separate  halves  of  the  block  in  opposite  directions. 

The  top  half  of  the  turbine  cylinder  having  been 
lifted  off,  the  spindle  is  set  relatively  to  the  bottom 
half  by  means  of  the  lower  thrust-block  screw  G.  This 
screw  is  then  locked  in  position  and  the  top  half  of 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE    117 

the  cover  then  lowered  into  place.  With  this  method 
great  care  must  necessarily  be  exercised  when  lowering 
the  top  cover;  otherwise  the  brass  dummy  rings  may 
be  damaged. 

A  safer  method  is  to  set  the  dummy  rings  in  the 
center  of  the  grooves  of  the  spindle,  and  then  to  lower 
the  cover,  with  less  possibility  of  contact.  There 
being  usually  plenty  of  side  clearance  between  the 
blades  of  a  turbine,  it  may  be  deemed  quite  safe  to 
lock  the  thrust-block  in  its  "position,  by  screwing  the 
screws  G  up  lightly,  and  then  to  turn  on  steam  and 
begin  running  slowly. 

Next,  the  spindle  may  be  very  carefully  and  gradually 
worked  in  the  required  direction,  namely,  in  that  direc- 
tion which  will  tend  to  bring  the  dummy  rings  and 
groove  walls  into  contact,  until  actual  but  very  light 
contact  takes  place.  The  slightest  noise  made  by  the 
rubbing  parts  inside  the  turbine  can  be  detected  by 
placing  one  end  of  a  metal  rod  onto  the  casing  in 
vicinity  of  the  dummy  pistons,  and  letting  the  other 
end  press  hard  against  the  ear.  Contact  between  the 
dummy  rings  and  spindle  being  thus  demonstrated, 
the  spindle  must  be  moved  back  by  the  screws,  but 
only  by  the  slightest  amount  possible.  The  merest 
fraction  of  a  turn  is  enough  to  break  the  contact, 
which  is  all  that  is  required.  In  performing  this 
operation  it  is  important,  during  the  axial  movements 
of  the  spindle,  to  adjust  the  halves  of  the  thrust-block 
so  that  there  can  exist  no  possible  play  which  would 
leave  the  spindle  free  to  move  axially  and  probably 
vibrate  badly. 


Ii8  STEAM  TURBINES 

After  ascertaining  the  condition  of  the  dummy  rings, 
attention  might  next  be  turned  to  the  thrust-block, 
which  must  not  on  any  account  be  tightened  up  too 
much.  It  is  sufficient  to  say  that  the  actual  require- 
ments are  such  as  will  enable  a  very  thin  film  of  oil 
to  circulate  between  each  wall  of  the  spindle  thrust- 
grooves  and  the  brass  thrust-blocks  ring.  In  other 
words,  there  should  be  no  actual  pressure,  irrespec- 
tive of  that  exerted  by  the  spindle  when  running,  upon 
the  thrust-block  rings,  due  to  the  separate  halves 
having  been  nipped  too  tightly.  The  results  upon  a 
test  of  considerable  friction  between  the  spindle  and 
thrust-rings  are  obvious. 

The  considerations  outlined  regarding  balancing 
pistons  and  dummy  rings  can  be  dispensed  with  in  con- 
nection with  impulse  turbines  of  the  De  Laval  and 
Rateau  types,  and  also  with  double-flow  turbines  of  a 
type  which  does  not  possess  any  dummies.  The  same 
general  considerations  respecting  blade  conditions  and 
thrust-blocks  are  applicable,  especially  to  the  latter 
type.  With  pure  so-called  impulse  turbines,  where 
the  blade  clearances  are  comparatively  large,  the  pre» 
liminary  blade  inspection  should  be  devoted  to  the 
mechanical  condition  of  the  blade  edges  and  passages. 
As  the  steam  velocities  of  these  types  are  usually 
higher,  the  importance  of  minimizing  the  skin  friction 
and  eliminating  the  possibility  of  eddies  is  great. 

Although  steam  leakage  through  the  valves  of  a 
turbine  may  not  materially  affect  its  steam  consump- 
tion, unless  it  be  the  leakage  through  the  overload 
valve  during  a  run  on  normal  full  load,  a  thorough 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     119 

examination  of  all  valves  is  advocated  for  many  reasons. 
In  a  turbine  the  main  steam-inlet  valve  is  usually 
operated  automatically  from  the  governor;  and  whether 
it  be  of  the  pulsating  type,  admitting  the  steam  in 
blasts,  or  of  the  non-pulsating  throttling  type,  it  is 
equally  essential  to  obtain  the  least  possible  friction 
between  all  moving  and  stationary  parts.  Similar  re- 
marks apply  to  the  main  governor,  and  any  sensitive 
transmitting  mechanism  connecting  it  with  any  of  the 
turbine  valves.  If  a  safety  or  "runaway"  governor 
is  possessed  by  the  machine  to  be  tested,  this  should 
invariably  be  tried  under  the  requisite  conditions  be- 
fore proceeding  farther.  The  object  of  this  governor 
being  automatically  to  shut  off  all  steam  from  the 
turbine,  should  the  latter  through  any  cause  rise  above 
the  normal  speed,  it  is  often  set  to  operate  at  about 
12  to  15  per  cent,  above  the  normal.  Thus,  a  turbine 
revolving  at  about  3000  revolutions  per  minute  would 
be  closed  down  at,  say,  3500,  which  would  be  within 
the  limit  of  "safe"  speed. 

IMPORTANCE  OF  OILING  SYSTEM  AND  WATER  SERVICE 

The  oil  question,  being  important,  should  be  solved 
in  the  early  stages  previously,  if  possible,  to  any  official 
or  unofficial  consumption  tests.  Whether  the  oil  be 
supplied  to  the  turbine  bearings  by  a  self-contained 
system  having  the  oil  stored  in  the  turbine  bedplate 
or  by  gravity  from  a  separate  oil  source,  does  not 
affect  the  question  in  its  present  aspect.  The  necessary 
points  to  investigate  are  four  in  number,  and  may  be 
headed  as  follows: 


120  STEAM  TURBINES 

(a)  Examination  of  pipes  and  partitions  for  oil 
leakage. 

(£)  Determination  of  volume  of  oil  flowing  through 
each  bearing  per  unit  of  time. 

(c)  Examination  for  signs  of  water  in  oil. 

(d)  Determination  of  temperature  rise  between  inlet 
and  outlet  of  oil  bearings. 

The  turbine  supplied  with  oil  by  the  gravity  or  any 
other  separate  system  holds  an  advantage  over  the 
ordinary  self-contained  machine,  inasmuch  as  the  oil 
pipes  conveying  oil  into  and  from  the  bearings  can 
be  easily  approached  and,  if  necessary,  repaired.  On 
the  other  hand,  the  machine  possessing  its  own  oil 
tank,  cooling  chamber  and  pump  is  somewhat  at  a 
disadvantage  in  this  respect,  as  a  part  of  the  sytsem 
is  necessarily  hidden  from  view,  and,  further,  it  is  not 
easily  accessible.  The  leakage  taking  place  in  any 
system,  if  there  be  any,  must,  however,  be  detected 
and  stopped. 

Fig.  63  is  given  to  illustrate  a  danger  peculiar  to 
the  self-contained  oil  system,  in  which  the  oil  and 
oil-cooling  chambers  are  situated  adjacently  in  the 
turbine  bedplate.  One  end  of  the  bedplate  only  is 
shown;  B  is  a  cast-iron  partition  dividing  the  oil  cham- 
ber C  from  the  oil-cooling  chamber  D.  Castings  of 
this  kind  have  sometimes  a  tendency  to  sponginess 
and  the  trouble  consequent  upon  this  weakness  would 
take  the  form  of  leakage  between  the  two  chambers. 
Of  course  this  is  only  a  special  case,  and  the  conditions 
named  are  hardly  likely  to  exist  in  every  similarly 
designed  plant.  The  capacity  of  oil,  and  especially 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE    121 

of  hot  oil,  to  percolate  through  the  most  minute  pores 
is  well  known.  Consequently,  in  advocating  extreme 
caution  when  dealing  with  oil  leakage,  no  apology  is 
needed. 

It  may  be  stated  without  fear  of  contradiction  that 
the  oil  in  a  self-contained  system,  namely,  a  system 
in  which  the  oil,  stored  in  a  reservoir  near  or  under- 
neath the  turbine,  passes  only  through  that  one  tur- 


FIG.    63 

bine's  bearings,  and  immediately  back  to  the  storage 
compartment,  deteriorates  more  rapidly  than  when 
circulating  around  an  "entire"  system,  such  as  the 
gravity  or  other  analogous  system.  In  the  latter,  the 
oil  tanks  are  usually  placed  a  considerable  distance 
from  the  turbine  or  turbines,  with  the  oil-cooling 
arrangements  in  fairly  close  proximity.  The  total 
length  of  the  oil  circuit  is  thus  considerably  increased, 
incidentally  increasing  the  relative  cooling  capacity  of 
the  whole  plant,  and  thereby  reducing  the  loss  of  oil 
by  vaporization. 


122  STEAM  TURBINES 

The  amount  of  oil  passing  through  the  bearings  can 
be  ascertained  accurately  by  measurement.  With  a 
system  such  as  the  gravity  it  is  only  necessary  to  run 
the  turbine  up  to  speed,  turn  on  the  oil,  and  then,  over 
a  period,  calculate  the  volume  of  oil  used  by  measur- 
ing the  fall  of  level  in  the  storage  tank  and  multiplying 
by  its  known  cross-sectional  area.  In  those  cases 
where  the  return  oil,  after  passing  through  the  bear- 
ings, is  delivered  back  into  the  same  tank  from  which 
it  is  extracted,  it  is  of  course  necessary,  during  the 
period  of  test,  to  divert  this  return  into  a  separate 
temporary  receptacle.  Where  the  system  possesses 
two  tanks,  one  delivery  and  one  return  (a  superior 
arrangement),  this  additional  work  is  unnecessary. 
The  same  method  can  be  applied  to  individual  turbines 
pumping  their  own  oil  from  a  tank  in  the  bedplate; 
the  return  oil,  as  previously  described,  being  tempora- 
rily prevented  from  running  back  to  the  supply. 

The  causes  of  excessive  oil  consumption  by  bearings 
are  many.  There  is  an  economical  mean  velocity  at 
which  the  oil  must  flow  along  the  revolving  spindle; 
also  an  economical  mean  pressure,  the  latter  diminish- 
ing from  the  center  of  the  bearing  toward  the  ends. 
The  aim  of  the  economist  must  therefore  be  in  the 
direction  of  adjusting  these  quantities  correctly  in 
relation  to  a  minimum  supply  of  oil  per  bearing;  and 
the  principal  factors  capable  of  variation  to  attain 
certain  requirements  are  the  several  bearing  clearances 
measured  as  annular  orifices,  and  the  bearing  diameters. 

It  is  not  always  an  easy  matter  to  detect  the  presence 
of  water  in  an  oil  system,  and  this  difficulty  is  increased 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE    123 

in  large  circuits,  as  the  water,  when  the  oil  is  not  flow- 
ing, generally  filters  to  the  lowest  members  and  pipes 
of  the  system,  where  it  cannot  usually  be  seen.  A  con- 
siderable quantity  of  water  in  any  system,  however, 
indicates  its  presence  by  small  globular  deposits  on 
bearings  and  spindles,  and  in  the  worst  cases  the  water 
can  clearly  be  seen  in  a  small  sample  tapped  from  the 
oil  mains.  There  is  only  one  effective  method  of 
ridding  the  oil  of  this  water,  and  this  is  by  allowing  the 
whole  mass  of  oil  in  the  system  to  remain  quiescent 
for  a  few  days,  after  which  the  water,  which  falls  to 
the  lowest  parts,  can  be  drained  off.  A  simple  method 
of  clearing  out  the  system  is  to  pump  all  the  oil  the 
whole  circuit  contains  through  the  filters,  and  thence 
to  a  tank  from  which  all  water  can  be  taken  off. 
One  of  the  ordinary  supply  tanks  used  in  the  gravity 
system  will  serve  this  purpose,  should  a  temporary 
tank  not  be  at  hand.  If  necessary,  the  headers  and 
auxiliary  pipes  of  the  system  can  be  cleaned  out  before 
circulating  the  oil  again,  but  as  this  is  rather  a  large 
undertaking,  it  need  only  be  resorted  to  in  serious 
cases. 

It  is  seldom  possible  to  discover  the  correct  and 
permanent  temperature  rise  of  the  circulating  oil  in  a 
turbine  within  the  limited  time  usually  alloted  for  a 
test.  After  a  continuous  run  of  one  hundred  hours 
it  is  possible  that  the  temperature  at  the  bearing  out- 
lets may  be  lower  than  it  was  after  the  machine  had 
run  for,  say,  only  twenty  hours.  As  a  matter  of  fact 
an  oil-temperature  curve  plotted  from  periodical  read- 
ings taken  over  a  continuous  run  of  considerable 


I24 


STEAM  TURBINES 


length  usually  reaches  a  maximum  early,  afterward 
falling  to  a  temperature  about  which  the  fluctuations 
are  only  slight  during  the  remainder  of  the  run.  Fig. 
64  illustrates  an  oil-temperature  curve  plotted  from 
readings  taken  over  a  period  of  twenty-four  hours. 
In  this  case  the  oil  system  was  of  the  gravity  descrip- 
tion, the  capacity  of  the  turbine  being  about  6000 
kilowatts.  The  bearings  were  of  the  ordinary  white- 
metal  spherical  type.  Over  extended  runs  of  hundreds 


FIG.   64 

and  even  thousands  of  hours,  the  above  deductions 
may  be  scarcely  applicable.  Running  without  break 
for  so  long,  a  small  turbine  circulating  its  own  lubricant 
would  possibly  require  a  renewal  of  the  oil  before  the 
run  was  completed,  in  the  main  owing  to  excessive 
temperature  rise  and  consequent  deterioration  of  the 
quality  of  the  oil.  Under  these  conditions  the  proba- 
bilities are  that  several  temperature  fluctuations  might 
occur  before  the  final  maximum,  and  more  or  less 
constant,  temperature  was  reached.  In  this  connec- 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     125 

tion,  however,  the  results  obtained  are  to  a  very  large 
extent  determined  by  the  general  mechanical  design 
and  construction  of  the  oiling  system  and  turbine.  A 
reference  to  Fig.  63  again  reveals  at  once  a  weakness 


FIG.   65 

in  that  design,  namely,  the  unnecessarily  close  prox- 
imity in  which  the  oil  and  water  tanks  are  placed. 

A  design  of  thermometer  cup  suitable  for  oil  ther- 
mometers is  given  in  Fig.  65  in  which  A  is  an  end  view 
of  the  turbine  bedplate,  B  is  a  turbine  bearing  and  C 
and  D  are  the  inlet  and  outlet  pipes,  respectively, 


126  STEAM  TURBINES 

The  thermometer  fittings,  which  are  placed  as  near  the 
bearing  as  is  practicable,  are  made  in  the  form  of  an 
angular  tee  fitting,  the  oil  pipes  being  screwed  into 
its  ends.  The  construction  of  the  oil  cup  and  tee 
piece  is  shown  in  the  detail  at  the  left  where  A  is  the 
steel  tee  piece,  into  which  is  screwed  the  brass  ther- 
mometer cup  B.  The  hollow  bottom  portion  of  this 
cup  is  less  than  -fa  of  an  inch  in  thickness.  The  tcp 
portion  of  the  bored  hole  is  enlarged  as  shown,  and  into 
this,  around  the  thermometer,  is  placed  a  non-con- 
ducting material.  The  cup  itself  is  generally  filled 
with  a  thin  oil  of  good  conductance. 

Allied  to  the  oil  system  of  a  turbine  plant  is  the  water 
service,  of  comparatively  little  importance  in  connec- 
tion with  single  self-contained  units  of  small  capacity, 
where  the  entire  service  simply  consists  of  a  few  coils 
and  pipes,  but  of  the  first  consideration  in  large  in- 
stallations having  numerous  separate  units  supplied 
by  oil  and  water  from  an  exterior  source.  The  largest 
turbine  units  are  often  supplied  with  water  for  cooling 
the  bearings  and  other  parts  liable  to  attain  high  tem- 
perature. Although  the  water  used  for  cooling  the 
bearings  indirectly  supplements  the  action  taking 
place  in  the  separate  oil  coolers,  it  is  of  necessity  a 
separate  auxiliary  service  in  itself,  and  the  complexity 
of  the  system  is  thus  added  to.  A  carefully  constructed 
water  service,  however,  is  hardly  likely  to  give  trouble 
of  a  mechanical  nature.  The  more  serious  deficiencies 
usually  arise  from  conditions  inherent  to  the  design, 
and  as  such  must  be  approached. 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE    127 

SPECIAL  TURBINE  FEATURES  TO  BE   INQUIRED  INTO 

Before  leaving  the  prime  mover  itself,  and  proceed- 
ing to  the  auxiliary  plant  inspection,  it  may  be  well  to 
instance  a  few  special  features  relating  to  the  general 
conduct  of  a  turbine,  which  it  is  the  duty  of  a  tester 
to  inquire  into:  There  are  certain  specified  qualifica- 
tions which  a  machine  must  hold  when  running  under 
its  commercial  conditions,  among  these  being  lack  of 
vibration  of  both  turbine  and  machinery  driven,  be  it 
generator  or  fan,  the  satisfactory  running  of  auxiliary 
turbine  parts  directly  driven  from  the  turbine  spindle, 
minimum  friction  between  the  driving  mediums,  such 
as  worm-wheels,  pumps,  fans,  etc.,  slight  irregularities 
of  construction,  often  resulting  in  heated  parts  and 
excessive  friction  and  wear,  and  must  therefore  be 
detected  and  righted  before  the  final  test.  Further- 
more, those  features  of  design  —  and  they  are  not  in- 
frequent in  many  machines  of  recent  development  — 
which,  in  practice,  do  not  fulfil  theoretical  expectations, 
must  be  re-designed  upon  lines  of  practical  consistency. 
The  experienced  tester's  opinion  is  often  at  this  point 
invaluable.  To  illustrate  the  foregoing,  Figs.  66,  67, 
and  68  are  given,  representing,  respectively,  three 
distinct  phases  in  the  evolution  of  a  turbine  part, 
namely,  the  coupling.  Briefly,  an  ordinary  coupling 
connecting  a  driving  and  a  driven  shaft  becomes 
obstinate  when  the  two  separate  spindles  which  it 
connects  are  not  truly  alined.  The  desire  of  turbine 
manufacturers  has  consequently  been  to  design  a 
flexible  coupling,  capable  of  accommodating  a  certain 


128 


STEAM   TURBINES 


want  of  alinement  between  the  two  spindles  without 
in  any  way  affecting  the  smooth  running  of  the  whole 
unit. 

In  Fig.  66  A  is  the  turbine  spindle  end  and  B  the 
generator  spindle  end,  which  it  is  required  to  drive. 
It  will  be  seen  from  the  cross-sectional  end  view  that 


FIG.   66 


both  spindle  ends  are  squared,  the  coupling  C,  with  a 
square  hole  running  through  it,  fitting  accurately  over 
both  spindle  ends  as  shown.  Obviously  the  fit  be- 
tween the  coupling  and  spindle  in  this  case  must  be 


FIG.   67 

close,  otherwise  considerable  wear  would  take  place; 
and  equally  obvious  is  the  fact  than  any  want  of 
alinement  between  the  two  spindles  A  and  B  will  be 
accompanied  by  a  severe  strain  upon  the  coupling,  and 
incidentally  by  many  other  troubles  of  operation  of 
which  this  inability  of  the  coupling  to  accommodate 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     129 

itself  to  a   little  want  of  alinement  is  the  inherent 
cause. 
Looking  at  the  coupling  illustrated  in  Fig.  67,  it 


130  STEAM  TURBINES 

will  be  seen  that  something  here  is  much  better  adapted 
to  dealing  with  troubles  of  alinement.  The  turbine 
and  generator  spindles  A  and  B,  respectively,  are 
coned  at  the  ends,  and  upon  these  tapered  portions  are 
shrunk  circular  heads  C  and  D  having  teeth  upon  their 
outer  circumferences.  Made  in  halves,  and  fitting 
over  the  heads,  is  a  sleeve-piece,  with  teeth  cut  into 
its  inner  bored  face.  The  teeth  of  the  heads  and  sleeve 
are  proportioned  correctly  to  withstand,  without 
strain,  the  greatest  pressure  liable  to  be  thrown  upon 
them.  There  is  practically  no  play  between  the  teeth, 
but  there  exists  a  small  annular  clearance  between 
the  periphery  of  the  heads  and  the  inside  bore  of  the 
sleeve,  which  allows  a  slight  lack  of  alinement  to  exist 
between  the  two  spindles,  without  any  strain  what- 
ever being  felt  by  the  coupling  sleeve  E.  The  nuts 
F  and  G  prevent  any  lateral  movement  of  the  coupling 
heads  C  and  D.  For  all  practical  requirements  this 
type  of  coupling  is  satisfactory,  as  the  clearances 
allowed  between  sliding  sleeve  and  coupling  heads 
can  always  be  made  sufficient  to  accommodate  a  con- 
siderable want  of  alinement,  far  beyond  anything 
which  is  likely  to  occur  in  actual  practice.  Perhaps 
the  only  feature  against  it  is  its  lack  of  simplicity  of 
construction  and  corresponding  costliness. 

The  type  illustrated  in  Fig.  68  is  a  distinct  advance 
upon  either  of  the  two  previous  examples,  because, 
theoretically  at  least,  it  is  capable  of  successfully 
accommodating  almost  any  amount  of  spindle  move- 
ment. The  turbine  and  generator  spindle  ends,  A  and 
B,  have  toothed  heads  C  and  D  shrunk  upon  them, 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     131 

the  heads  being  secured  by  the  nuts  E  and  F.  The 
teeth  in  this  case  are  cut  in  the  enlarged  ends  as  shown. 
A  sleeve  G,  made  in  halves,  fits  over  the  heads,  and 
the  teeth  cut  in  each  half  engage  with  those  of  their 
respective  heads.  All  the  teeth  and  teeth  faces  are 
cut  radially,  and  a  little  side  play  is  allowed. 

THE  CONDENSER 

To  some  extent,  as  previously  remarked,  the  con- 
denser and  condensing  arrangements  are  instrumental 
in  determining  the  lines  upon  which  a  test  ought  to  be 
carried  out.  In  general,  the  local  features  of  a  plant 
restrict  the  tester  more  or  less  in  the  application  of  his 
general  methods.  A  thorough  inspection,  including 
some  preliminary  tests  if  necessary,  is  as  essential  to 
the  good  conduct  of  the  condensing  plant  as  to  the 
turbine  above  it.  It  may  be  interesting  to  outline 
the  usual  course  this  inspection  takes,  and  to  draw 
attention  to  a  few  of  the  special  features  of  different 
plants.  For  this  purpose  a  type  of  vertical  condenser 
is  depicted  in  Fig.  69.  Its  general  principle  will  be 
gathered  from  the  following  description: 

Exhaust  steam  from  the  turbine  flows  down  the  pipe 
T  and  enters  the  condenser  at  the  top  as  shown,  where 
it  at  once  comes  into  contact  with  the  water  tubes  in 
W.  These  tubes  fill  an  annular  area,  the  central  un- 
tubed  portion  below  the  baffle  cap  B  forming  the  vapor 
chamber.  The  condensed  steam  falls  upon  the  bottom 
tube-plate  P  and  is  carried  away  by  the  pipe  5  lead- 
ing to  the  water  pump  H.  The  Y  pipe  E  termina- 
ting above  the  level  of  the  water  in  the  condenser 


132 


STEAM   TURBINES 


enters  the  dry-air  pump  section  pipe  A.  Cold  circu- 
lating water  enters  the  condenser  at  the  bottom, 
through  the  pipe  /,  and  entering  the  water  chamber  X 
proceeds  upward  through  the  tubes  into  the  top-water 
chamber  Y,  and  from  there  out  of  the  condenser 


FIG.   69 

through  the  exit  pipe.  It  will  be  observed  that  the 
vapor  extracted  through  the  plate  P  passes  on  its  jour- 
ney out  of  the  condenser  through  the  cooling  chamber 
D  surrounded  by  the  cold  circulating  water.  This,  of 
course,  is  a  very  advantageous  feature.  At  R  is  the 
condenser  relief,  at  U  the  relief  valve  for  the  water 
chambers. 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     133 

A  new  condenser,  especially  if  it  embody  new  and 
untried  features,  generally  requires  a  little  time  and 
patience  ere  the  best  results  can  be  obtained  from  it. 
Perhaps  the  quickest  and  most  satisfactory  method  of 
getting  at  the  weak  points  of  this  portion  of  a  plant  is 
to  test  the  various  elements  individually  before  apply- 
ing a  strict  load  test.  Thus,  in  dealing  with  a  condenser 
similar  to  that  illustrated  in  Fig.  69,  the  careful  tester 
would  probably  make,  in  addition  to  a  throrough  me- 
chanical examination,  three  or  four  individual  vacuum 
and  water  tests.  A  brief  description  of  these  will  be 
given.  The  water  test,  the  purpose  of  which  is  to 
discover  any  leakage  from  the  tubes,  tube-plates, 
water  pipes,  etc.,  into  portions  of  the  steam  or  air 
chambers,  should  be  made  first. 

WATER  TESTS  OF  CONDENSER 

The  condenser  is  first  thoroughly  dried  out,  par- 
ticular care  being  given  to  the  outside  of  the  tubes 
and  the  bottom  tube-plate  P.  Water  is  then  circu- 
lated through  the  tubes  and  chambers  for  an  hour  or 
two,  after  which  the  pumps  are  stopped,  all  water  is 
allowed  to  drain  out  and  a  careful  examination  is 
made  inside.  Any  water  leaking  from  the  tubes  above 
the  bottom  baffle-plate  will  ultimately  be  deposited 
upon  that  plate.  It  is  essential  to  stop  this  leakage 
if  there  be  any,  otherwise  the  condensed  steam  meas- 
ured during  the  consumption  test  will  be  increased  to 
the  extent  of  the  leakage.  A  slight  leakage  in  a  large 
condenser  will  obviously  not  affect  the  results  to  any 
serious  extent.  The  safest  course  to  adopt  when  a 


I34  STEAM  TURBINES 

leak  is  discovered  and  it  is  found  inopportune  to  effect 
immediate  repair  is  to  measure  the  actual  volume  of 
leakage  over  a  specified  period,  and  the  quantity  then 
being  known  it  can  be  subtracted  from  the  volume  of 
the  condensed  steam  at  the  end  of  the  consumption 
test. 

It  is  equally  essential  that  no  leakage  shall  occur 
between  the  bottom  tube-plate  P  and  the  tube  ends. 
The  soundness  of  the  tube  joints,  and  the  joint  at  the 
periphery  of  the  tube-plate  can  be  tested  by  well  cover- 
ing the  plate  with  water,  the  water  chamber  W  and 
cooling  chamber  having  been  previously  emptied,  and 
observing  the  under  side  of  the  plate.  It  must  be 
admitted  that  the  practice  of  measuring  the  extent  of 
a  water  leak  over  a  period,  and  afterward  with  this 
knowledge  adjusting  the  obtained  quantities,  is  not 
always  satisfactory.  On  no  account  should  any  test 
be  made  with  considerable  water  leakage  inside  the 
condenser.  The  above  method,  however,  is  perhaps 
the  most  reliable  to  be  followed,  if  during  its  conduct 
the  conditions  of  temperature  in  the  condenser  are 
made  as  near  to  the  normal  test  temperature  as  pos- 
sible. There  are  many  condensers  using  salt  water  in 
their  tubes,  and  in  these  cases  it  would  seem  natural 
to  turn  to  some  analytical  method  of  detecting  the 
amount  of  saline  and  foreign  matter  leaking  into  the 
condensed  steam.  Unless,  however,  only  approximate 
results  are  required,  such  methods  are  not  advocated. 
There  are  many  reasons  why  they  cannot  be  relied 
upon  for  accurate  results,  among  these  being  the  varia- 
tion in  the  percentage  of  saline  matter  in  the  sea-water, 


PROPER  METHOD  OF  TESTING  STEAM  TURBINE     135 

the  varying  temperature  of  the  condenser  tubes 
through  which  the  water  flows,  and  the  uncertainty 
of  such  analysis,  especially  where  the  percentage 
leakage  of  pure  saline  matter  is  comparatively  small. 

THE  VACUUM  TEST 

Having  convinced  himself  of  the  satisfactory  con- 
duct of  the  condenser  under  the  foregoing  simple 
preparatory  water  tests,  the  tester  may  safely  pass 
to  considerations  of  vacuum.  There  exists  a  good 
old-fashioned  method  of  discovering  the  points  of 
leakage  in  a  vacuum  chamber,  namely,  that  of  apply- 
ing the  flame  of  a  candle  to  all  seams  and  other  vul- 
nerable spots,  which  in  the  location  of  big  leaks  is 
extremely  valuable.  Assuming  that  the  turbine  joints 
and  glands  have  been  found  capable  of  preventing  any 
inleak  of  air,  with  only  a  small  absolute  pressure  of 
steam  or  air  inside  it,  and,  further,  an  extremely  im- 
portant condition,  with  the  turbine  casing  at  high  and 
low  temperatures,  separately,  a  vacuum  test  can  be 
conducted  on  the  condenser  alone. 

This  test  consists  of  three  operations.  In  the  first 
place  a  high  vacuum  is  obtained  by  means  of  the  air 
pump,  upon  the  attainment  of  which  communication 
with  everything  else  is  closed,  and  results  noted.  The 
second  operation  consists  in  repeating  the  above  with 
the  water  circulating  through  the  condenser  tubes,  the 
results  in  this  case  also  being  carefully  tabulated.  Be- 
fore conducting  the  third  test,  the  condensers  must  be 
thoroughly  warmed  throughout,  by  running  the  turbine 
for  a  short  time  if  necessary,  and  after  closing  com- 


136  STEAM  TURBINES 

munication  with  everything,  allowing  the  vacuum  to 
slowly  fall. 

A  careful  consideration  and  comparison  of  the  fore- 
going tests  will  reveal  the  capabilities  of  the  condenser 
in  the  aspect  in  which  it  is  being  considered,  and  will 
suggest  where  necessary  the  desirable  steps  to  be  taken. 


VJ 

TESTING  A  STEAM  TURBINE1 

SPECIAL  AUXILIARY  PLANT  FOR  CONSUMPTION  TEST 

THERE  are  one  or  two  points  of  importance  in  the 
conduct  of  a  test  on  a  turbine  and  these  will  be  briefly 
touched  upon.  Fig.  70  illustrates  the  general  arrange- 
ment of  the  special  auxiliary  plant  necessary  for 
carrying  through  a  consumption  test,  when  the  tur- 
bine exhaust  passes  through  a  surface  condenser. 
The  condensed  steam,  after  leaving  the  condenser, 
passes  along  the  pipe  A  to  the  pump,  and  is  then  forced 
along  the  pipe  B  (leading  under  ordinary  circum- 
stances to  the  hot-well),  through  the  main  water 
valve  C  directly  to  the  measuring  tanks.  To  enter 
these  the  water  has  to  pass  through  the  valves  D  and 
E,  while  the  valves  F  and  G  are  for  quickly  emptying 
the  tanks  when  necessary,  being  of  a  larger  bore  than 
the  inlet  valves.  The  inlet  pipes  H  I  are  placed  di- 
rectly above  the  outlet  valves,  and  thus,  when  re- 
quired, before  any  measurements  are  taken,  the 
water  can  flow  directly  through  the  outlet  valves, 
the  pipes  terminating  only  a  short  distance  above 
them,  away  to  an  auxiliary  tank  or  directly  to  the 

'Contributed  to  Ptfioer  by  Thomas  Franklin. 
137 


138  STEAM  TURBINES 

hot-well.  Levers  K  and  L  fulcrumed  at  J  and  /  are 
connected  to  the  valve  spindles  by  auxiliary  levers. 
The  valve  arrangement  is  such  that  by  pulling  down 
the  lever  K  the  inlet  valve  D  is  opened  and  the  inlet 
valve  E  is  closed.  Again,  by  pulling  down  the  lever 
L  the  outlet  valve  F  is  closed,  while  the  outlet  valve 
G  is  also  simultaneously  closed. 


O~Yrun.pj|      B  ^/ 


FIG.    70 

During  a  consumption  test  the  valves  are  operated 
in  the  following  manner:  The  lever  K  is  pulled  down, 
which  opens  the  inlet  valve  to  the  first  tank  and  closes 
that  to  the  second  The  bottom  lever  L,  however,  is 
lifted,  which  for  the  time  being  opens  the  outlet  valve 
F,  and  incidentally  opens  the  valve  G;  the  latter 
valve  can,  however,  for  the  moment  be  neglected. 
When  the  turbine  is  started,  and  the  condensed  steam 


TESTING  A  STEAM  TURBINE  139 

begins  to  accumulate  in  the  condenser,  the  water  is 
pumped  along  the  pipes  and,  both  the  inlet  and  out- 
let valves  on  the  first  tank  being  open,  passes  through, 
without  any  being  deposited  in  the  tank,  to  the  drain. 
This  may  be  continued  until  all  conditions  are  right 
for  a  consumption  test  and,  the  time  being  carefully 
noted,  lever  L  is  quickly  pulled  down  and  the  valves 
F  and  G  closed.  The  first  tank  now  gradually  fills, 
and  after  a  definite  period,  say  fifteen  minutes,  the 
lever  K  is  pushed  up,  thus  diverting  the  flow  into  the 
second  tank.  While  the  latter  is  filling,  the  water  in 
the  first  tank  is  measured,  and  the  tank  emptied  by 
a  large  sluice  valve,  not  shown. 

The  operation  of  alternately  filling,  measuring,  and 
emptying  the  two  measuring  tanks  is  thus  carried 
on  until  the  predetermined  time  of  duration  of  test 
has  expired,  when  the  total  water  as  measured  in  the 
tanks,  and  representing  the  amount  of  steam  con- 
densed during  that  time,  is  easily  found  by  adding 
together  the  quantities  given  at  each  individual 
measurement. 

All  that  are  necessary  to  insure  successful  results 
from  a  plant  similar  to  this  are  care  and  accuracy  in 
its  operation  and  construction.  Undoubtedly  in 
most  cases  it  is  preferable  to  weigh  the  condensed 
steam  instead  of  measuring  the  volume  passed,  and 
from  that  to  calculate  the  weight.  If  dependence  is 
being  placed  upon  the  volumetric  method,  it  is  advis- 
able to  lengthen  the  duration  of  the  test  considerably, 
and  if  possible  to  measure  the  feed-water  evaporated 
at  the  same  time.  Such  a  course,  however,  would 


140  STEAM  TURBINES 

necessitate  little  change,  and  none  of  a  radical  nature, 
from  the  arrangement  described.  Where,  however, 
the  measuring  method  is  adopted,  the  all-important 
feature,  requiring  on  the  tester's  part  careful  per- 
sonal investigation,  is  the  graduation  of  the  tanks. 
It  facilitates  this  operation  very  considerably  when 
the  receptacles  are  graduated  upon  a  weight  scale. 
That  is  to  say,  whether  or  not  a  vertical  scale  showing 
the  actual  hight  of  water  be  placed  inside  the  tank, 
it  is  advisable  to  have  a  separate  scale  indicating  at 
once  to  the  attendant  the  actual  contents,  by  weight, 
of  the  tank  at  any  time.  It  is  the  tester's  duty  to 
himself  to  check  the  graduation  of  this  latter  scale 
by  weighing  the  water  with  which  he  performs  the 
operation  of  checking. 

Apart  from  the  foregoing,  there  is  little  to  be  said 
about  the  measuring  apparatus.  As  has  been  stated, 
accuracy  of  result  depends  in  this  connection,  as  in 
all  others,  upon  careful  supervision  and  sound  and 
accurate  construction,  and  this  the  tester  can  only 
positively  insure  by  exhaustive  inspection  in  the  one 
case  and  careful  deliberation  in  the  conduct  of  the 
other. 

It  will  be  readily  understood  that  the  procedure  — 
and  this  implies  some  limitations  —  of  a  test  is  to  an 
extent  controlled  by  the  conditions,  or  particular  en- 
vironment of  the  moment.  This  is  strictly  true,  and 
as  a  consequence  it  is  often  impossible,  in  a  maker's 
works,  for  example,  to  obtain  every  condition,  coin- 
ciding with  those  specified,  which  are  to  be  had  on 
the  site  of  final  operation  only.  For  this  reason  it 


TESTING   A  STEAM  TURBINE  141 

would  appear  best  to  reserve  the  final  and  crucial 
test  of  a  machine,  which  test  usually  in  the  operating 
sense  restricts  a  prime  mover  in  certain  directions 
with  regard  to  its  auxiliary  plant,  etc.,  until  the  ma- 
chine has  been  finally  erected  on  its  site.  Obviously, 
unless  a  machine  had  become  more  or  less  standard- 
ized, a  preliminary  consumption  test  would  be  neces- 
sary, but  once  this  primary  qualification  respecting 
consumption  had  been  satisfactorily  settled,  there 
appears  to  be  no  reason  why  exhaustive  tests  in  other 
directions  should  not  all  be  carried  out  upon  the  site, 
where  the  conditions  for  them  are  so  much  more 
favorable. 

When  the  steam  consumption  of  a  steam  turbine 
is  so  much  higher  than  the  guaranteed  quantity,  it 
usually  takes  little  less  than  a  reconstruction  to  put 
things  right.  The  minor  qualifications  of  a  machine, 
however,  which  can  be  examined  into  and  tested  with 
greater  ease,  and  usually  at  considerably  less  expense, 
upon  the  site,  and  consequently  under  specified  con- 
ditions, may  be  advantageously  left  over  until  that 
site  is  reached,  where  it  is  obvious  that  any  shortcom- 
ings and  general  deficiency  in  performance  will  be 
more  quickly  detected  and  diagnosed. 

TEST  LOADS  FROM  THE  TESTER'S  VIEW-POINT 

Before  proceeding  to  describe  the  points  of  actual 
interest  in  the  consumption  test,  a  few  considerations 
respecting  test  loads  will  be  dealt  with  from  the  tes- 
ter's point  of  view.  Here  again  we  often  find  our- 
selves restricted,  to  an  extent,  by  the  surrounding 


142  STEAM  TURBINES 

conditions.  The  very  first  considerations,  when  under- 
taking to  carry  out  a  consumption  test,  should  be 
devoted  to  obtaining  the  steadiest  possible  lead.  It 
may  be,  and  is  in  many  cases,  that  circumstances 
are  such  as  to  allow  a  steady  electrical  load  to  be 
obtained  at  almost  any  time.  On  the  other  hand  an 
electrical  load  of  any  description  is  sometimes  not 
procurable  at  all,  without  the  installation  of  a  special 
plant  for  the  purpose.  In  such  cases  a  mechanical 
friction  load,  as,  for  example,  that  obtained  by  the 
water  brake,  is  sometimes  available,  or  can  easily  be 
procured.  Whereas,  however,  this  type  of  load  may 
be  satisfactory  for  small  machines,  it  is  usually  quite 
impossible  for  use  with  large  units,  of,  say,  5000  kilo- 
watts and  upward.  It  is  seldom,  however,  that 
turbines  are  made  in  large  sizes  for  directly  driving 
anything  but  electrical  plants,  although  there  is  every 
possibility  of  direct  mechanical  driving  between  large 
steam  turbines  and  plants  of  various  descriptions, 
shortly  coming  into  vogue,  so  that  usually  there  exist 
some  facilities  for  obtaining  an  electrical  load  at  both 
the  maker's  works  and  upon  the  site  of  operation. 

One  consideration  of  importance  is  worth  inquiring 
into,  and  this  has  relation  to  the  largest  turbo-genera- 
tors supplied  for  power-station  and  like  purposes. 
Obviously,  the  testing  of,  say,  a  yooo-kilowatt  alter- 
nator by  any  standard  electrical-testing  method  must 
entail  considerable  expense,  if  such  a  test  is  to  be 
carried  out  in  the  maker's  works.  Nor  would  this 
expense  be  materially  decreased  by  transferring  the 
operations  to  the  power-station,  and  there  erecting 


TESTING  A  STEAM  TURBINE  143 

the  necessary  electrical  plant  for  obtaining  a  water 
load,  or  any  other  installation  of  sufficient  capacity 
to  carry  the  required  load  according  to  the  rated  full 
capacity  of  the  machine. 

Assuming,  then,  that  there  exist  no  permanent 
facilities  at  either  end,  namely  the  maker's  works 
and  the  power  station,  for  adequately  procuring  a 
steady  electrical-testing  load  of  sufficient  capacity, 
there  still  remains,  in  this  instance,  an  alternative 
source  of  pow'er  which  is  usually  sufficiently  elastic 
to  serve  all  purposes,  and  this  is  of  course  the  total 
variable  load  procurable  from  the  station  bus-bars. 
It  is  conceivable  that  one  out  of  a  number  of  machines 
running  in  parallel  might  carry  a  perfectly  steady 
load,  the  latter  being  a  fraction  of  a  total  varying 
quantity,  leaving  the  remaining  machines  to  receive 
and  deal  with  all  fluctuations  which  might  occur. 
Even  in  the  event  of  there  being  only  two  machines, 
it  is  possible  to  maintain  the  load  on  one  of  them 
comparatively  steady,  though  the  percentage  varia- 
tion in  load  on  either  side  of  the  normal  would  in  the 
latter  case  be  greater  than  in  the  previous  one.  This 
is  accomplished  by  governor  regulation  after  the 
machines  have  been  paralleled-  For  example,  assum- 
ing three  turbo-alternators  of  similar  make  and  capac- 
ity to  be  running  in  parallel,  each  machine  carrying 
exactly  one-third  of  the  total  distributed  load,  it  is 
fair  to  regard  the  governor  condition,  allowing  for 
slight  mechanical  disparities  of  construction,  of  all 
three  machines  as  being  similar;  and  even  in  the  case 
of  three  machines  of  different  capacity  and  construe- 


144  STEAM  TURBINES 

tion,  the  governor  conditions  when  the  machines  are 
paralleled  are  more  or  less  relatively  and  permanently 
fixed  in  relation  to  one  another.  In  other  words, 
while  the  variation  in  load  on  each  machine  is  the 
same,  the  relative  variation  in  the  governor  condition 
must  be  constant. 

By  a  previously  mentioned  system  of  governor 
regulation,  however,  it  is  possible,  considering  again 
for  a  moment  the  case  of  three  machines  in  parallel, 
by  decreasing  the  sensitiveness  of  one  governor  only, 
to  accommodate  nearly  all  the  total  variation  in  load 
by  means  of  the  two  remaining  machines,  the  unre- 
sponsiveness  of  the  one  governor  to  change  in  speed 
maintaining  the  load  on  that  machine  fairly  constant. 
By  this  method,  at  any  rate,  the  variation  in  load  on 
any  one  machine  can  be  minimized  down  to,  say,  3 
per  cent,  either  side  of  the  normal  full  load. 

There  is  another  and  more  positive  method  by 
which  a  perfectly  steady  load  can  be  maintained  upon 
one  machine  of  several  running  in  parallel.  This 
may  be  carried  out  as  follows:  Suppose,  in  a  station 
having  a  total  capacity  of  20,000  kilowatts,  there  are 
three  machines,  two  of  6000  kilowatts  each,  and  one 
of  8000  kilowatts,  and  it  is  desired  to  carry  out  a 
steady  full-load  test  upon  one  of  the  6000  kilowatts 
units.  Assuming  that  the  test  is  to  be  of  six  hours' 
duration,  and  that  the  conditions  of  load  fluctuations 
upon  the  station  are  well  known,  the  first  step  to  take 
is  to  select  a  period  for  the  test  during  which  the  total 
load  upon  all  machines  is  not  likely  to  fall  below,  say, 
8000  kilowatts.  The  tension  upon  the  governor 


TESTING  A  STEAM  TURBINE 


145 


spring  of  the  turbine  to  be  tested  must  then  be  ad- 
justed so  that  the  machine  on  each  peak  load  is  taxed 
to  its  utmost  normal  capacity;  and  even  when  the 
station  load  falls  to  its  minimum,  the  load  from  the 
particular  machine  shall  not  be  released  sufficiently 
to  allow  it  to  fall  below  6000  kilowatts.  Under  these 
conditions,  then,  it  may  be  assumed  that  although 
the  load  on  the  test  machine  will  vary,  it  cannot  fall 
below  6000  kilowatts.  Therefore,  all  that  remains 
to  be  done  to  insure  a  perfectly  steady  load  equal  to 
the  normal  full  load  of  the  machine,  or  6000  kilowatts, 
is  to  fix  the  main  throttle  or  governing  valve  in  such 
a  position  that  the  steam  passing  through  at  constant 
pressure  is  just  capable  of  sustaining  full  speed  under 
the  load  required.  When  this  method  is  adopted, 
it  is  desirable  to  fix  a  simple  hight-ad justing  and  lock- 
ing mechanism  to  the  governing-valve  spindle.  The 
load  as  read  on  the  indicating  wattmeter  can  then 
be  very  accurately  varied  until  correct,  and  farther 
varied,  if  necessary,  should  any  change  occur  in  the 
general  conditions  which  might  either  directly  or  in- 
directly bring  about  a  change  of  load. 

PREPARING  THE  TURBINE  FOR  TESTING 

All  preliminary  labors  connected  with  a  test  being 
satisfactorily  disposed  of,  it  only  remains  to  place  the 
turbines  under  the  required  conditions,  and  to  then 
proceed  with  the  test.  For  the  benefit  of  those  inex- 
perienced in  the  operation  of  large  turbines,  we  will 
assume  that  such  a  machine  is  about  to  be  started 
for  the  purpose  outlined. 


146  STEAM  TURBINES 

It  is  always  advisable  to  make  a  strict  practice  of 
getting  all  the  auxiliary  plant  under  way  before  start- 
ing up  the  turbine.  In  handling  a  turbine  plant  the 
several  operations  might  be  carried  through  in  the 
following  order: 

(1)  Circulating   oil    through   all   bearings   and   oil 
chambers.1 

(2)  Starting  of  condenser  circulating-water  pumps, 
and  continuous  circulation  of  circulating  water  through 
the  tubes  of  condenser. 

(3)  Starting  of  pump  delivering  condensed  steam 
from  the  condenser  hot-well  to  weighing  tanks. 

(4)  Starting  of  air  pump,  vacuum  being  raised  as 
high  as  possible  within  condenser. 

(5)  Sealing  of  turbine  glands,  whether  of  liquid  or 
steam  type,  no  adjustment  of  the  quantity  of  sealing 
fluid  being  necessary,  however,  at  this  point. 

(6)  Adjustment  of  valves  on  and  leading  to  the 
water-weighing  tanks. 

(7)  Opening  of  main  exhaust  valve  or  valves  be- 
tween turbine  and  condenser. 

(8)  Starting  up  of  turbine  and  slowly  running  to 
speed. 

(9)  Application  of  load,  and  adjustment  of  gland- 
sealing  steam. 

The   running  to  speed  of  large   turbo-alternators 

1  In  a  self-contained  system,  where  the  oil  pump  is  usually  driven  from  the 
turbine  spindle,  this  would  of  course  be  impossible.  In  the  gravity  and  allied 
systems,  however,  it  should  always  be  the  first  operation  performed.  The  tests 
for  oil  consumption,  described  previously,  having  been  carried  out,  it  is  assumed 
that  suitable  means  have  been  adopted  to  restrict  the  total  oil  flow  through  the 
bearings  to  a  minimum  quantity. 


TESTING   A  STEAM   TURBINE  147 

requires  considerable  care,  and  should  always  be 
done  slowly;  that  is  to  say  the  rate  of  acceleration 
should  be  slow.  It  is  well  known  that  the  vibration 
of  a  heavy  unit  is  accompanied  by  a  synchronous  or 
non-synchronous  vibration  of  the  foundation  upon 
which  it  rests.  The  nearest  approach  to  perfect 
synchronism  between  unit  and  foundation  is  obtained 
by  a  gradual  rise  in  speed.  A  machine  run  up  to 
speed  too  quickly  might,  after  passing  the  critical 
speed,  settle  down  with  little  visible  vibration,  but  at 
a  later  time,  even  hours  after,  suddenly  begin  vibrat- 
ing violently  from  no  apparent  cause.  The  chances 
of  this  occurring  are  minimized  by  slow  and  careful 
running  to  speed. 

Whether  the  machine  being  tested  is  one  of  a  num- 
ber running  in  parallel,  or  a  single  unit  running  on  a 
steady  water  load,  the  latter  should  in  all  cases  be 
thrown  on  gradually  until  full  load  is  reached.  A 
preliminary  run  of  two  or  three  hours  —  whenever 
possible  —  should  then  be  made,  during  which  ample 
opportunity  is  afforded  for  regulating  the  conditions 
in  accordance  with  test  requirements.  The  tester 
will  do  well  during  the  last  hour  of  this  trial  run  to 
station  his  recorders  at  their  several  posts  and,  for 
a  short  time  at  least,  to  have  a  complete  set  of  read- 
ings taken  at  the  correct  test  intervals.  This  more 
particularly  applies  to  the  electrical  water,  superheat 
and  vacuum  readings.  In  the  case  of  a  turbo-alter- 
nator the  steadiness  obtainable  in  the  electrical  load 
may  determine  the  frequency  of  readings  taken,  bovh 
electrical  and  otherwise.  On  a  perfectly  steady  water- 


148  STEAM  TURBINES 

tank  load,  for  example,  it  may  be  sufficiently  adequate 
to  read  all  wattmeters,  voltmeters,  and  ammeters 
from  standard  instruments  at  from  one-  to  two-minute 
intervals.  Readings  at  half-minute  intervals,  how- 
ever, should  be  taken  with  a  varying  load,  even  when 
the  variation  is  only  slight. 

The  water-measurement  readings  may  of  course  be 
taken  at  any  suitable  intervals,  the  time  being  to  an 
extent  determined  by  the  size  of  the  measuring  tanks 
or  the  capacity  of  the  weighing  machine  or  machines. 
When  designing  the  measuring  apparatus,  the  object 
should  be  to  minimize,  within  economical  and  prac- 
tical range,  the  total  number  of  weighings  or  measure- 
ments necessary.  Consequently,  no  strict  time  of 
interval  between  individual  weighings  or  measure- 
ments can  be  given  in  this  case.  It  may  be  said,  how- 
ever, that  it  is  not  desirable  to  take  these  at  anything 
less  than  five-minute  intervals.  Under  ordinary  cir- 
cumstances a  three-  to  five-minute  interval  is  sufficient 
in  the  case  of  all  steam-pressure,  vacuum  —  including 
mercurial  columns  and  barometer  —  superheat  and 
temperature  readings. 

GLAND  AND  HOT-WELL  REGULATION 

There  are  two  highly  important  features  requiring 
more  or  less  constant  attention  throughout  a  tesvt, 
namely  the  gland  and  hot-well  regulation.  For  the 
present  purpose  we  may  assume  that  the  glands  are 
supplied  with  either  steam  or  water  for  sealing  them. 
All  steam  supplied  to  the  turbine  obviously  goes  to 
swell  the  hot-well  contents,  and  to  thus  increase  the 


TESTING   A   STEAM   TURBINE  149 

total  steam  consumption.  The  ordinary  steam  gland 
is  in  reality  a  pressure  gland.  At  both  ends  of  the 
turbine  casing  is  an  annular  chamber,  surrounding 
the  turbine  spindle  at  the  point  where  it  projects 
through  the  casing.  A  number  of  brass  rings  on  either 
side  of  this  chamber  encircle  the  spindle,  with  only  a 
very  fine  running  clearance  between  the  latter  and 
themselves.  Steam  enters  the  gland  chamber  at  a 
slight  pressure,  and,  when  a  vacuum  exists  inside  the 
turbine  casing,  tends  to  flow  inward.  The  pressure, 
however,  inside  the  gland  is  increased  until  it  exceeds 
that  of  the  atmosphere  outside,  and  by  maintaining 
it  at  this  pressure  it  is  obvious  that  no  air  can  pos- 
sibly enter  the  turbine  through  the  glands,  to  destroy 
the  vacuum.  The  above  principle  must  be  borne  in 
mind  during  a  test  upon  a  turbine  having  steam-fed 
glands.  Perhaps  the  best  course  to  follow  —  in  view 
of  the  economy  of  gland  steam  consumption  neces- 
sary—  is  as  follows: 

During  the  preliminary  non-test  run,  full  steam  is 
turned  into  both  glands  while  the  vacuum  is  being 
raised,  and  maintained  until  full  load  has  been  on 
the  turbine  for  some  little  time.  The  vacuum  will  by 
this  time  have  probably  reached  its  maximum,  and 
perhaps  fallen  to  a  point  slightly  lower,  at  which  hight 
it  may  be  expected  to  remain,  other  conditions  also 
remaining  constant.  The  gland  steam  must  now  be 
gradually  turned  off  until  the  amount  of  steam  vapor 
issuing  from  the  glands  is  almost  imperceptible. 
This  should  not  lower  the  vacuum  in  the  slightest 
degree.  By  gradual  degrees  the  gland  steam  can  be 


150  STEAM  TURBINES 

still  farther  cut  down,  until  no  steam  vapor  at  all 
can  be  discerned  issuing  from  the  gland  boxes.  This 
reduction  should  be  continued  until  a  point  is  reached 
at  which  the  vacuum  is  affected,  when  it  must  be 
stopped  and  the  amount  of  steam  flowing  to  the  gland 
again  increased  very  slightly,  just  enough  to  bring 
the  vacuum  again  to  its  original  hight.  The  steam 
now  passing  into  the  glands  is  the  minimum  re- 
quired under  the  conditions,  and  should  be  main- 
tained as  nearly  constant  as  possible  throughout  the 
test.  Practically  all  steam  entering  the  glands  is 
drawn  into  the  turbine,  and  thence  to  the  condenser, 
and  under  the  circumstances  it  may  be  assumed  the 
increase  in  steam  consumption  arising  from  this  source 
is  also  a  minimum. 

There  is  one  mechanical  feature  which  has  an  im- 
portant bearing  upon  the  foregoing  question,  and 
which  it  is  one  of  the  tester's  duties  to  investigate. 
This  is  illustrated  in  Fig.  71,  which  shows  a  turbine 
spindle  projecting  through  the  casing.  The  gland 
box  is  let  into  the  casing  as  shown.  Brass  rings  A 
calked  into  the  gland  box  encircle  the  shaft  on  either 
side  of  the  annular  steam  space  5.  As  the  clearance 
between  the  turbine  spindle  and  the  rings  A  is  in  a 
measure  instrumental  in  determining  the  amount  of 
steam  required  to  maintain  a  required  pressure  inside 
the  chamber,  it  is  obvious  that  this  clearance  should 
be  minimum.  An  unnecessarily  large  clearance  means 
a  proportionally  large  increase  in  gland  steam  con- 
sumption and  vice  versa. 

When  the  turbine  glands  are  sealed  with  water,  all 


TESTING  A  STEAM  TURBINE  151 

water  leakage  which  takes  place  into  the  turbine,  and 
ultimately  to  the  condenser  hot-well,  must  be  meas- 
ured and  subtracted  from .  the  hot-well  contents  at 
the  end  of  a  test. 
The  foregoing  remarks  would  not  apply  to  those 


FIG.    71 

cases  in  which  the  gland  supply  is  drawn  from  and 
returned  to  the  hot-well,  or  a  pipe  leading  from  the 
hot-well.  Then  no  correction  would  be  necessary, 
as  all  water  used  for  gland  purposes  might  be  assumed 
as  being  taken  from  the  measuring  tanks  and  returned 
again  in  time  for  same  or  next  weighing  or  measure- 
ment. 


152  STEAM  TURBINES 

GENERAL  CONSIDERATIONS 

There  are  a  few  principal  elementary  points  which 
it  is  necessary  always  to  keep  in  mind  during  the 
conduct  of  a  test.  Among  these  are  the  effects  of 
variation  in  vacuum,  superheat,  initial  steam  pres- 
sure, and,  as  already  indicated,  in  load.  There  exist 
many  rules  for  determining  the  corrections  necessi- 
tated by  this  variation.  For  example,  it  is  often 
assumed  that  9  degrees  Fahrenheit,  excess  or  other- 
wise, above  or  below  that  specified,  represents  an  in- 
crease or  reduction  in  efficiency  of  about  i  per  cent. 
It  is  probable  that  the  percentage  increase  or  decrease 
in  steam  consumption,  in  the  case  of  superheat,  can 
be  more  reliably  calculated  than  in  other  cases,  as, 
for  example,  vacuum;  but  the  increase  cannot  be  said 
to  be  due  solely  to  the  variation  in  superheat.  In 
other  words,  the  individuality  of  the  particular  turbine 
being  tested  always  contributes  something,  however 
small  this  something  may  be,  to  the  results  obtained. 

These  remarks  are  particularly  applicable  where 
vacuum  is  concerned.  Here  again  rules  exist,  one  of 
these  being  that  every  additional  inch  of  vacuum 
increases  the  economy  of  the  turbine  by  something 
slightly  under  half  a  pound  of  steam  per  kilowatt- 
hour.  But  a  moment's  consideration  convinces  one 
of  the  utter  unreliability  of  such  rules  for  general 
application.  It  is,  for  instance,  well  known  that 
many  machines,  when  under  test,  have  demonstrated 
that  the  total  increase  in  the  water  rate  is  very  far 
from  constant.  A  machine  tested,  for  example,  gave 


TESTING  A  STEAM  TURBINE 


153 


approximately  the  following  results,  the  object  of  the 
test  being  to  discover  the  total  increase  in  the  water 
rate  per  inch  decrease  in  vacuum : 

From  27  inches  to  26  inches,  4.5  per  cent. 

From  26.2  inches  to  24.5  inches,  2.5  per  cent. 

This  illustrates  to  what  an  extent  the  ratio  of  increase 
can  vary,  and  it  must  be  borne  in  mind  that  it  is  very 
probable  that  the  variation  is  different  in  different 
types  and  sizes  of  machines. 

There  can  exist,  therefore,  no  empirical  rules  of  a 
reliable  nature  upon  which  the  tester  can  base  his 
deductions.  The  only  way  calculated  to  give  satis- 
faction is  to  conduct  a  series  of  preliminary  tests  upon 
the  turbine  undergoing  observation,  and  from  these 
to  deduce  all  information  of  the  nature  required, 
which  can  be  permanently  recorded  in  a  set  of  curves 
for  reference  during  the  final  official  tests. 

In  conclusion,  it  must  be  admitted  that  many  pub- 
lished tests  outlining  the  performances  of  certain 
makes  of  turbine  are  unreliable.  To  determine 
honestly  the  capabilities  of  any  machine  in  the  direc- 
tion of  steam  economy  is  an  operation  requiring  time, 
and  unbiased  and  accurate  supervision.  By  means 
of  such  assets  as  "floating  quantities,"  short  tests 
during  exceptionally  favorable  conditions,  and  dis- 
regard of  the  vital  necessity  of  running  a  test  under 
the  proper  specified  conditions,  it  is  comparatively 
easy  to  obtain  results  apparently  highly  satisfactory, 
but  which  under  other  conditions  might  be  just 
the  reverse.  These  considerations  are,  however,  un- 
worthy of  the  tester  proper. 


VII 

AUXILIARIES  FOR  STEAM  TURBINES1 

THE  JET  CONDENSER 

THE  jet  condenser  illustrated  in  Fig.  72  is  singularly 
well  adapted  for  the  turbine  installation.  As  the 
type  has  not  been  so  widely  adopted  as  the  more 
common  forms  of  jet  condenser  and  the  surface  types, 
it  may  prove  of  interest  to  describe  briefly  its  general 
construction  and  a  few  of  its  special  features  in  rela- 
tion to  tests. 

Referring  to  the  figure,  C  is  the  main  condenser 
body.  Exhaust  steam  enters  at  the  left-hand  side 
through  the  pipe  E,  condensing  water  issuing  through 
the  pipe  D  at  the  opposite  side.  Passing  through  the 
short  conical  pipe  P,  the  condensing  water  enters 
the  cylindrical  chamber  W  and  falls  directly  upon 
the  spraying  cone  S.  The  hight  of  this  spraying  cone 
is  determined  by  the  tension  upon  the  spring  T,  below 
the  piston  R,  the  latter  being  connected  to  the  cone 
by  a  spindle  L.  An  increase  of  the  water  pressure 
inside  the  chamber  W  will  thus  compress  the  spring, 
and  the  spraying  cone  being  consequently  lowered 
increases  the  aperture  between  it  and  the  sloping 

1  Contributed  to  Power  by  Thomas  Franklin. 


AUXILIARIES   FOR   STEAM   TURBINES 


155 


lower  wall  of  the  chamber  W,  allowing  a  greater  vol- 
ume of  water  to  be  sprayed.  The  piston  R  inciden- 
tally prevents  water  entering  the  top  vapor  chamber 
V .  From  the  foregoing  it  can  be  seen  that  this  con- 
denser is  of  the  contra-flow  type,  the  entering  steam 


FIG.    72 

coming  immediately  into  contact  with  the  sprayed 
water.  The  perforated  diaphragm  plate  F  allows 
the  vapor  to  rise  into  the  chamber  V ,  from  which  it 
is  drawn  through  the  pipe  A  to  the  air  pump.  A 
relief  valve  U  prevents  an  excessive  accumulation 


156  STEAM  TURBINES 

of  pressure  in  the  vapor  chamber,  this  valve  being 
obviously  of  delicate  construction,  capable  of  opening 
upon  a  very  slight  increase  of  the  internal  pressure 
over  that  of  the  atmosphere.  Condensed  steam  and 
circulating  water  are  together  carried  down  the  pipe 
B  to  the  well  Z,  from  which  a  portion  may  be  carried 
off  as  feed  water,  and  the  remainder  cooled  and  passed 
through  the  condenser  again.  Under  any  circum- 
stances, whether  the  air  pump  is  working  or  not,  a 
certain  percentage  of  the  vapor  in  the  condenser  is 
always  carried  down  the  pipe  B,  and  this  action  alone 
creates  a  partial  vacuum,  thus  rendering  the  work  of 
the  air  pump  easier.  As  a  matter  of  fact,  a  fairly  high 
vacuum  can  be  maintained  with  the  air  pump  closed 
down,  and  only  the  indirect  pumping  action  of  the 
falling  water  operating  to  rarify  the  contents  of  the 
condenser  body.  It  is  customary  to  place  the  con- 
denser forty  or  more  feet  above  the  circulating-water 
pump,  the  latter  usually  being  a  few  feet  below  the 
turbine. 

FEATURES  DEMANDING  ATTENTION 

When  operating  a  condenser  of  this  type,  the  most 
important  features  requiring  preliminary  inspection 
and  regulation  while  running  are: 

(a)  Circulating-water  regulation. 

(b)  Freedom  of  all  mechanical  parts  of  spraying 
mechanism. 

(c)  Relief-valve  regulation. 

(d)  Water-cooling  arrangements. 

The  tester  will,  however,  devote  his  attention  to 


AUXILIARIES   FOR  STEAM  TURBINES  157 

a  practical  survey  of  the  condenser  and  its  auxiliaries, 
before  running  operations  commence. 

A  preliminary  vacuum  test  ought  to  be  conducted 
upon  the  condenser  body,  and  the  exhaust  piping 
between  the  condenser  and  turbine.  To  acomplish 
this  the  circulating-water  pipe  D  can  be  filled  with 
water  to  the  condenser  level.  The  relief  valve  should 
also  be  water-sealed.  Any  existing  leakage  can  thus 
be  located  and  stopped. 

Having  made  the  condenser  as  tight  as  possible 
within  practical  limits,  vacuum  might  be  again  raised 
and,  with  the  same  parts  sealed,  allowed  to  fall  slowly 
for,  say,  ten  minutes.  A  similar  test  over  an  equal 
period  may  then  be  conducted  with  the  relief  valve 
not  water-sealed.  A  comparison  of  the  times  taken 
for  an  equal  fall  of  vacuum  in  inches,  under  the  differ- 
ent conditions,  during  the  above  two  tests,  will  reveal 
the  extent  of  the  leakage  taking  place  through  the 
relief  valve.  It  seems  superfluous  to  add  that  the 
fall  of  vacuum  in  both  the  foregoing  tests  must  not 
be  accelerated  in  any  way,  but  must  be  a  result  simply 
of  the  slight  inevitable  leakage  which  is  to  be  found  in 
every  system. 

On  a  comparatively  steady  load,  and  with  conse- 
quently only  small  fluctuation  in  the  volume  of  steam 
to  be  condensed,  the  conditions  are  most  favorable 
for  regulating  the  amount  of  circulating  water  neces- 
sary. Naturally,  an  excess  of  water  above  the  re- 
quired minimum  will  not  affect  the  pressure  conditions 
inside  the  condenser.  It  does,  however,  increase 
the  quantity  of  water  to  be  handled  from  the  hot- 


158  STEAM  TURBINES 

well,  and  incidentally  lowers  the  temperature  there, 
which,  whether  the  feed-water  pass  through  econo- 
mizers or  otherwise,  is  not  advisable  from  an  eco- 
nomical standpoint.  Thus  there  is  an  economical 
minimum  of  circulating  water  to  be  aimed  at,  and, 
as  previously  stated,  it  can  best  be  arrived  at  by  run- 
ning the  turbine  under  normal  load  and  adjusting 
the  flow  of  the  circulating  water  by  regulating  the 
main  valve  and  the  tension  upon  the  spring  T.  Under 
abnormal  conditions,  the  breakdown  of  an  air  pump, 
or  the  sudden  springing  of  a  bad  leak,  for  instance, 
the  amount  of  circulating  water  can  be  increased  by 
a  farther  opening  of  the  main  valve  if  necessary,  and 
a  relaxation  of  the  spring  tension  by  hand;  or,  the 
spring  tension  might  be  automatically  changed  im- 
mediately upon  the  vacuum  falling. 

The  absolute  freedom  of  all  moving  parts  of  the 
spraying  mechanism  should  be  one  of  the  tester's 
first  assurances.  To  facilitate  this,  it  is  customary 
to  construct  the  parts,  with  the  exception  of  the  springs, 
of  brass  or  some  other  non-corrosive  metal.  The 
spraying  cone  must  be  thoroughly  clean  in  every 
channel,  to  insure  a  well-distributed  stream  of  water. 
Nor  is  it  less  important  that  careful  attention  be 
given  to  the  setting  and  operation  of  the  relief  valve, 
as  will  be  seen  later.  The  obvious  object  of  such  a 
valve  is  to  prevent  the  internal  condenser  pressure 
ever  being  maintained  much  higher  than  the  atmos- 
pheric pressure.  A  number  of  carefully  designed 
rubber  flap  valves,  or  one  large  one,  have  been  found 
to  act  successfully  for  this  purpose,  although  a  bal- 


AUXILIARIES   FOR  STEAM  TURBINES  159 

anced  valve  of  more  substantial  construction  would 
appear  to  be  more  desirable. 

IMPORTANCE  OF  RELIEF  VALVES 

The  question  of  relief  valves  in  turbine  installations 
is  an  important  one,  and  it  seems  desirable  at  this 
point  to  draw  attention  to  another  necessary  relief 
valve  and  its  function,  namely  the  turbine  atmos- 
pheric valve.  As  generally  understood,  this  is  placed 
between  the  turbine  and  condenser,  and,  should  the 
pressure  in  the  latter,  owing  to  any  cause,  rise  above 
that  of  the  atmosphere,  it  opens  automatically  and 
allows  the  exhaust  steam  to  flow  through  it  into  the 
atmosphere,  or  into  another  condenser. 

A  general  diagrammatic  arrangement  of  a  steam 
turbine,  condenser,  and  exhaust  piping  is  shown  in 
Fig.  2.  Connected  to  the  exhaust  pipe  B,  near  to  the 
condenser,  is  the  automatic  atmospheric  valve  D, 
from  which  leads  the  exhaust  piping  E  to  the  atmos- 
phere. The  turbine  relief  valve  is  shown  at  F,  and 
the  condenser  relief  valve  at  G.  The  main  exhaust 
valve  between  turbine  and  condenser  is  seen  at  H. 
We  have  here  three  separate  relief  valves:  one,  F,  to 
prevent  excessive  pressure  in  the  turbine:  the  second, 
D,  an  atmospheric  valve  opening  a  path  to  the  air, 
and,  in  addition  to  preventing  excessive  pressure 
accumulating,  also  helping  to  keep  the  temperature 
of  the  condenser  body  and  tubes  low;  the  third,  the 
condenser  relief  valve  G,  which  in  itself  ought  to  be 
capable  of  exhausting  all  steam  from  the  turbine, 
should  occasion  demand  it. 


160  STEAM  TURBINES 

Assuming  a  plant  of  this  description  to  be  operat- 
ing favorably,  the  conditions  would  of  necessity  be 
as  follows:  The  valves  F,  D,  and  G,  all  closed;  the 
valve  H  open.  Suppose  that,  owing  to  sudden  loss 
of  circulating  water,  the  vacuum  fell  to  zero.  The 
condenser  would  at  once  fill  with  steam,  a  slight  pres- 
sure would  be  set  up,  and  whichever  of  the  three  valves 
happened  to  be  set  to  blow  off  at  the  lowest  pressure 
would  do  so.  Now  it  is  desirable  that  the  first  valve 
to  open  under  such  circumstances  should  be  the  at- 
mospheric valve  D.  This  being  so,  the  condenser 
would  remain  full  of  steam  at  atmospheric  pressure 
until  the  attendant  had  had  time  to  close  the  main 
hand-  or  motor-operated  exhaust  valve  H,  which  he 
would  naturally  do  before  attempting  to  regain  the 
circulation  of  the  condensing  water.  Again,  assume 
the  installation  to  be  running  under  the  initial  condi- 
tions, with  the  atmospheric  valve  D  and  all  remaining 
valves  except  H  closed. 

Suppose  the  vacuum  again  fell  to  zero  from  a 
similar  cause,  and,  further,  suppose  the  atmospheric 
valve  D  failed  to  operate  automatically.  The  only 
valves  now  capable  of  passing  the  exhaust  steam  are 
the  turbine  and  condenser  relief  valves  F  and  G. 
Inasmuch  as  the  pressures  at  exhaust  in  the  turbine 
proper,  on  varying  load,  vary  over  a  considerably 
greater  range  than  the  small  fairly  constant  absolute 
pressures  inside  the  condenser,  it  is  obviously  neces- 
sary to  allow  for  this  factor  in  the  respective  setting 
of  these  two  relief  valves.  In  other  words,  the  ob- 
vious deduction  is  to  set  the  turbine  relief  valve  to 


AUXILIARIES   FOR  STEAM  TURBINES  161 

blow  off  at  a  higher  pressure  than  the  condenser  relief 
valve,  even  when  considering  the  question  with  re- 
spect to  condensing  conditions  only.  In  this  second 
hypothetical  case,  then,  with  a  closed  and  disabled 
atmospheric  valve,  the  exhaust  must  take  place 
through  the  condenser,  until  the  turbine  can  be  shut 
down,  or  the  circulating  water  regained  without  the 
former  course  being  found  necessary. 

There  is  one  other  remote  case  which  may  be 
assumed,  namely,  the  simultaneous  refusal  of  both 
atmospheric  and  condenser  relief  valves  to  open,  upon 
the  vacuum  inside  the  condenser  being  entirely  lost. 
The  exhaust  would  then  be  blown  through  the  turbine 
relief  valve  F,  until  the  plant  could  be  closed  down. 

Although  the  conditions  just  cited  are  highly  im- 
probable in  actual  practice,  it  can  at  once  be  seen  that 
to  insure  the  safety  of  the  condenser,  absolutely,  the 
turbine  relief  valve  must  be  set  to  open  at  a  compar- 
atively low  pressure,  say  40  pounds  by  gage,  or  there- 
abouts. To  set  it  much  lower  than  this  would  create 
a  possibility  of  its  leaking  when  the  turbine  was  making 
a  non-condensing  run,  and  when  the  pressure  at  the 
turbine  exhaust  end  is  often  above  that  of  the  atmos- 
phere. From  every  point  of  view,  therefore,  it  is 
advisable  to  make  a  minute  examination  of  all  relief 
valves  in  a  system,  and  before  a  test  to  insure  that 
these  valves  are  all  set  to  opeTi  at  their  correct  rela- 
tive pressures. 

It  must  be  admitted  that  the  practice  of  placing  a 
large  relief  valve  upon  a  condenser  in  addition  to  the 
atmospheric  exhausting  valve  is  by  no  means  common. 


162 


STEAM  TURBINES 


The  latter  valve,  where  surface  condensing  is  adopted, 
is  often  thought  sufficient,  working  in  conjunction 
with  a  quickly  operated  main  exhaust  valve.  Sim- 
ilarly, with  a  barometric  condenser  as  that  illustrated 
in  Fig.  72,  the  atmospheric  exhaust  valve  D  (seen  in 
Fig.  73)  is  sometimes  dispensed  with.  This  course 
is,  however,  objectionable,  for  upon  a  loss  of  vacuum 


FIG.  73 

in  the  turbine,  all  exhaust  steam  must  pass  through 
the  condenser  body,  or  the  entire  plant  be  closed  down 
until  the  vacuum  is  regained.  The  simple  construc- 
tion of  the  barometric icondenser,  however,  is  in  such 
an  event  much  to  its  advantage,  and  the  passage  of 
the  hot  steam  right  through  it  is  not  likely  to  seri- 
ously warp  or  strain  any  of  its  parts,  as  might  prob- 
ably happen  in  the  case  of  a  surface  condenser. 


AUXILIARIES   FOR   STEAM   TURBINES  163 

The  question  of  the  advisability  of  thus  adding 
to  a  plant  can  only  be  fairly  decided  when  all  condi- 
tions, operating  and  otherwise,  are  fully  known. 
For  example,  if  we  assume  a  large  turbine  to  be  oper- 
ating on  a  greatly  varying  load,  and  exhausting  into 
a  condenser,  as  that  in  Fig.  72,  and,  further,  having 
an  adequate  stand-by  to  back  it  up,  one's  obvious 
recommendation  would  be  to  equip  the  installation 
with  both  a  condenser  relief  valve  and  an  atmos- 
pheric valve,  in  addition,  of  course,  to  the  main 
exhaust  valve,  which  is  always  placed  between  the 
atmospheric  valve  and  condenser.  There  are  still 
other  considerations,  such  as  water  supply,  condition 
of  circulating  water,  style  of  pump,  etc.,  which  must 
all  necessarily  have  an  obvious  bearing  upon  the 
settlement  of  this  question;  so  that  generalization  is 
somewhat  out  of  place,  the  final  design  in  all  cases 
depending  solely  upon  general  principles  and  local 
conditions. 

OTHER  NECESSARY  FEATURES  OF  A  TEST 

In  connection  with  the  condenser,  of  any  type,  and 
its  auxiliaries,  there  remain  a  few  necessary  examina- 
tions and  operations  to  be  conducted,  if  it  is  desired 
to  obtain  the  very  best  results  during  the  test.  It 
will  be  sufficient  to  just  outline  them,  the  method  of 
procedure  being  well  known,  and  the  requirement 
of  any  strict  routine  being  unnecessary.  These  in- 
clude: 

(i)  A  thorough  examination  of  the  air-pump,  and, 
if  possible,  an  equally  careful  examination  of  dia- 


164  STEAM  TURBINES 

grams  taken  from  it  when  running  on  full  load.  Also 
careful  examination  of  the  piping,  and  of  any  other 
connections  between  the  air  pump  and  condenser,  or 
other  auxiliaries.  It  will  be  well  in  this  examination 
to  note  the  general  "lay"  of  the  air  pipes/ length, 
hight  to  which  they  rise  above  condenser  and  air 
pump,  facilities  for  drainage,  etc.,  as  this  information 
may  prove  valuable  in  determining  the  course  neces- 
sary to  rectify  deficiencies  which  may  later  be  found 
to  exist. 

(2)  In  a  surface  condenser,  inspection  of  the  pumps 
delivering  condensed  steam  to  the  measuring  tanks 
or  hot-well;  inspection  of  piping  between  the  con- 
denser and  the  pump,  and  also  between  the  pump  and 
measuring  tanks.     If  these  pumps  are  of  the  centrif- 
ugal  type  it   is  essential  to  insure,  for  the  purposes 
of  a  steam-consumption  test,  as  much  regularity  of 
delivery  as  possible. 

(3)  In  the  case  of  a  consumption  test  upon  a  tur- 
bine  exhausting   into   a   barometric   condenser,    and 
where  the  steam  consumed  is  being  measured  by  the 
evaporation  in  the  boiler  over  the  test  period,  time 
must  be  devoted  to  the  feed-pipes  between  the  feed- 
water  measuring  meter  or  tank  and  the  boilers.     Under 
conditions  similar  to  those  operating  in  a  plant  such 
as  that  shown  in   Fig.  72,  the  necessary  boiler  feed 
might  be  drawn  from  the  hot-well,  the  remainder  of 
the  hot-well  contents  probably  being  pumped  through 
water  coolers,  or  towers,  for  circulating  through  the 
condenser.    With    the    very  best  system,  it    is  pos- 
sible for  a  slight  quantity  of  oil  to  leak  into  the  exhaust 


AUXILIARIES   FOR  STEAM  TURBINES  165 

steam,  and  thence  to  the  hot-well.  In  its  passage, 
say  along  wooden  conduits,  to  the  measuring  tank  or 
meter,  this  water  would  probably  pass  through  a  num- 
ber of  filters.  The  efficiency  of  these  must  be  thor- 
oughly insured.  It  is  unusual,  in  those  cases  where 
a  simple  turbine  steam-consumption  test  is  being 
carried  out,  and  not  an  efficiency  test  of  a  complete 
plant,  to  pass  the  measured  feed-water  through  econ- 
omizers. Should  the  latter  course,  owing  to  special 
conditions,  become  necessary,  a  careful  examination 
of  all  economizer  pipes  would  be  necessary. 

(4)  The  very  careful  examination  of  all  thermom- 
eter pockets,  steam-  and  temperature-gage  holes,  etc., 
as  to  cleanliness,  non-accumulation  of  scale,  etc. 

SPECIAL  AUXILIARIES  NECESSARY 

Having  outlined  the  points  of  interest  and  impor- 
tance in  connection  with  the  more  permanent  features 
of  a  plant,  we  arrive  at  the  preparation  and  fitting  of 
those  special  auxiliaries  necessary  to  carry  on  the 
test. 

It  is  customary,  when  carrying  out  a  first  test,  upon 
both  prime  mover  and  auxiliaries,  to  place  every  im- 
portant stage  in  the  expansion  in  communication  with 
a  gage,  so  that  the  various  pressures  may  be  recorded 
and  later  compared  with  the  figures  of  actual  require- 
ment. To  do  this,  in  the  case  of  the  turbine,  it  is 
necessary  to  bore  holes  in  the  cover  leading  to  the 
various  expansion  chambers,  and  into  each  of  these 
holes  to  screw  a  short  length  of  steam  pipe,  having 
preferably  a  loop  in  its  length,  to  the  other  end  of 


i66 


STEAM  TURBINES 


which  the  gage  is  attached.  Fig.  74  illustrates,  dia- 
grammatically,  a  complete  turbine  installation,  and 
shows  the  various  points  along  the  course  taken  by 
the  steam  at  which  it  is  desirable  to  place  pressure 
gages.  The  figure  does  not  shew  the  high-pressure 
steam  pipe,  nor  any  of  the  turbine  valves.  With 


FIG.  74 

regard  to  these,  it  will  be  desirable  to  place  a  steam 
gage  in  the  pipe,  immediately  before  the  main  stop- 
valve,  and  another  immediately  after  it.  Any  fall 
of  pressure  between  the  two  sides  of  the  valve  can  thus 
be  detected.  To  illustrate  this  clearly,  Fig.  75  is 
given,  showing  the  valves  of  a  turbine,  and  the  posi- 
tion of  the  gages  connected  to  them.  The  two  gages 
E  and  F  on  either  side  of  the  main  stop-valve  A  are 


AUXILIARIES   FOR  STEAM  TURBINES  167 

also  shown.  The  steam  after  passing  through  the 
valve,  which,  in  the  case  of  small  turbines,  is  hand- 
operated,  goes  in  turn  through  the  automatic  stop- 
valve  B,  the  function  of  which  is  to  automatically 
shut  steam  off  should  the  turbine  attain  a  predeter- 
mined speed  above  the  normal,  the  steam  strainer  C, 
and  finally  through  the  governing  valve  D  into  the 
turbine.  As  shown,  gages  G  and  H  are  also  fitted 
on  either  side  of  the  strainer,  and  these,  in  conjunction 
with  gages  E  and  F,  will  enable  any  fall  in  pressure 


FIG.  75 

between  the  first  two  valves  and  the  governing  valve 
to  be  found.  Up  to  the  governing-valve  inlet  no 
throttling  of  the  steam  ought  to  take  place  under 
normal  conditions,  i.e.,  with  all  valves  open,  and 
consequently  any  fall  in  pressure  between  the  steam 
inlet  and  this  point  must  be  the  result  of  internal 
wire-drawing.  By  placing  the  gages  as  shown,  the 
extent  to  which  this  wire-drawing  affects  the  pres- 
sures obtainable  can  be  discovered. 

On  varying  and  even  on  normal  and  steady  full 
load,  the  steam  is  more  or  less  reduced  in  pressure 
after  passing  through  the  governing  valve  D;  a  gage  / 


1 68  STEAM  TURBINES 

must  consequently  be  placed  between  the  valve, 
preferably  on  the  valve  itself,  and  the  turbine.  Re- 
turning to  Fig.  74,  the  gages  shown  are  A,  B,  C,  D, 
and  E,  connected  to  the  first,  second,  third,  fourth, 
and  fifth  expansions;  also  F  in  the  turbine  and  exhaust 
space,  where  there  are  no  blades,  G  in  the  exhaust 
pipe  immediately  before  the  main  exhaust  valve  E 
(see  Fig.  73),  and  H  connected  to  the  condenser.  On 
condensing  full  load  it  is  probable  that  A,  B,  and  C 
will  all  register  pressures  above  the  atmosphere,  while 
gages  D,  E,  F,  and  G  will  register  pressures  below 
the  atmosphere,  being  for  this  purpose  vacuum  gages. 
On  the  other  hand,  with  a  varying  load,  and  conse- 
quently varying  initial  pressures,  one  or  two  of  the 
gages  may  register  pressure  at  one  moment  and  vac- 
uum at  another.  It  will  therefore  be  necessary  to 
place  at  these  points  compound  gages  capable  of 
registering  both  pressure  and  vacuum.  With  the 
pressures  in  the  various  stages  constantly  varying, 
however,  a  gage  is  not  by  any  means  the  most  reliable 
instrument  for  recording  such  variations.  The  con- 
stant swinging  of  the  finger  not  only  renders  accurate 
reading  at  any  particular  moment  both  difficult  and, 
to  an  extent,  unreliable,  but,  in  addition,  the  accom- 
panying sudden  changes  of  condition,  both  of  tem- 
perature and  pressure,  occurring  inside  the  gage  tube, 
in  a  comparatively  short  time  permanently  warp  this 
part,  and  thus  altogether  destroy  the  accuracy  of 
the  gage.  It  is  well  known  that  even  with  the  best 
steel-tube  gages,  registering  comparatively  steady 
pressures,  this  warping  of  the  tube  inevitably  takes 


AUXILIARIES   FOR  STEAM  TURBINES  169 

place.  The  quicker  deterioration  of  such  gage  tubes, 
when  the  gage  is  registering  quickly  changing  pres- 
sures, can  therefore  readily  be  conceived,  and  for 
this  reason  alone  it  is  desirable  to  have  all  gages, 
whatever  the  conditions  under  which  they  work, 
carefully  tested  and  adjusted  at  short  intervals.  If 
it  is  desired  to  obtain  reliable  registration  of  the  sev- 
eral pressures  in  the  different  expansions  of  a  turbine 
running  on  a  varying  load,  it  would  therefore  seem 
advisable  to  obtain  these  by  some  type  of  external 
spring  gage  (an  ordinary  indicator  has  been  found  to 
serve  well  for  this  purpose)  which  the  sudden  internal 
variations  in  pressure  and  temperature  cannot  dele- 
teriously  affect. 

In  view  of  the  great  importance  he  must  attach  to 
his  gage  readings,  the  tester  would  do  well  to  test 
and  calibrate  and  adjust  where  necessary  all  the 
gages  he  intends  using  during  a  test.  This  he  can  do 
with  a  standard  gage-testing  outfit.  By  this  means 
only  can  he  have  full  confidence  in  the  accuracy  of 
his  results. 

In  like  manner  it  is  his  duty  personally  to  super- 
vise the  connecting  and  arrangement  of  the  gages, 
and  the  preliminary  testing  for  leakage  which  can 
be  carried  out  simultaneously  with  the  vacuum  test 
made  upon  the  turbine  casing. 

WHERE  THERMOMETERS  ARE  REQUIRED 

Equally  important  with  the  foregoing  is  the  neces- 
sity of  calibrating  and  testing  of  all  thermometers 
used  during  a  test.  Where  possible  it  is  advisable 


170  STEAM  TURBINES 

to  place  new  thermometers  which  have  been  previously 
tested  at  all  points  of  high  temperature.  Briefly 
running  them  over,  the  points  at  which  it  is  necessary 
to  place  thermometers  in  the  entire  system  of  the 
steam  and  condensing  plant  are  as  follows: 

(1)  A  thermometer  in  the  steam  pipe  on  the  boiler, 
where  the  pipe  leaves  the  superheater. 

(2)  In  the  steam  pipe  immediately  in  front  of  the 
main  stop-valve,  near  point  E  in  Fig.  75. 

(3)  In  the  main  governing  valve  body  (see  /,  Fig. 
75)  on  the  inlet  side. 

(4)  In  the  main  governing  valve  body  on  the  tur- 
bine side,  which  will  register  temperatures  of  steam 
after  it  has  passed  through  the  valve. 

(5)  In    the   steam-turbine    high-pressure    chamber, 
giving  the  temperature  of  the  steam    before  it    has 
passed  through  any  blades. 

(6)  In  the  exhaust  chamber,  giving  the  tempera- 
ture of  steam  on  leaving  the  last  row  of  blades. 

(7)  In  the  exhaust  pipe  near  the  condenser. 

(8)  In  the  condenser  body. 

(9)  In  the  circulating-water  inlet  pipe  close  to  the 
condenser. 

(10)  In  the  circulating-water  outlet  pipe  close  to 
the  condenser. 

(n)  In  the  air-pump  suction  pipe  close  to  the 
condenser. 

(12)  In  the  air-pump  suction  pipe  close  to  the  air 
pump. 

It  is  not  advisable  to  place  at  those  vital  points, 
the  readings  at  which  directly  or  indirectly  affect  the 


AUXILIARIES   FOR  STEAM  TURBINES  171 

consumption,  two  thermometers,  say  one  ordinary 
chemical  thermometer  and  one  thermometer  of  the 
gage  type,  thus  eliminating  the  possibility  of  any 
doubt  which  might  exist  were  only  one  thermometer 
placed  there. 

There  is  no  apparent  reason  why  one  should  attempt 
to  take  a  series  of  temperature  readings  during  a 
consumption  test  on  varying  load.  The  tempera- 
tures registered  under  a  steady  load  test  can  be  ob- 
tained with  great  reliability,  but  on  a  varying  load, 
with  constantly  changing  temperatures  at  all  points, 
this  is  impossible.  This  is,  of  course,  owing  to  the 
natural  sluggishness  of  the  temperature-recording 
instruments,  of  whatever  class  they  belong  to,  in 
responding  to  changes  of  condition.  As  a  matter  of 
fact,  the  possibility  of  obtaining  correctly  the  entire 
conditions  in  a  system  running  under  greatly  varying 
loads  is  very  doubtful  indeed,  and  consequently  great 
reliance  cannot  be  placed  upon  figures  obtained  under 
such  conditions. 

A  few  simple  calculations  will  reveal  to  the  tester 
his  special  requirements  in  the  direction  of  measur- 
ing tanks,  piping,  etc.,  for  his  steam  consumption  test. 
Thus,  assuming  the  turbine  to  be  tested  to  be  of  3000 
kilowatt  capacity  normal  load,  with  a  guaranteed 
steam  consumption  of,  say,  14.5  pounds  per  kilowatt- 
hour,  he  calculates  the  total  water  rate  per  hour, 
which  in  this  case  would  be  43,500  pounds,  and  designs 
his  weighing  or  measuring  tanks  to  cope  with  that 
amount,  allowing,  of  course,  a  marginal  tank  volume 
for  overload  requirements. 


VIII 

TROUBLES  WITH   STEAM  TURBINE 
AUXILIARIES1 

THE  case  about  to  be  described  concerns  a  steam 
plant  in  which  there  were  seven  cross-compound 
condensing  Corliss  engines,  and  two  Curtis  steam 
turbines.  The  latter  were  each  of  1 5oo-kilowatt 
capacity,  and  were  connected  to  surface  condensers, 
dry-vacuum  pumps,  centrifugal,  hot-well  and  circu- 
lating pumps,  respectively.  In  the  illustration  (Fig. 
76),  the  original  lay-out  of  piping  is  shown  in  full  lines. 
Being  originally  a  reciprocating  'plant  it  was  difficult 
to  make  the  allotted  space  for  the  turbines  suitable 
for  their  proper  installation.  The  trouble  which 
followed  was  a  perfectly  natural  result  of  the  failure 
to  meet  the  requirements  of  a  turbine  plant,  and  the 
description  herein  given  is  but  one  example  of  a  great 
many  where  the  executive  head  of  a  concern  insists 
upon  controlling  the  situation  without  regard  to  en- 
gineering advice  or  common  sense. 

CIRCULATING    PUMP    FAILS    TO    MEET    GUARANTEE 

Observing  the  plan  view,  it  will  be  seen  that  the 
condensers  for  both  turbines  receive  their  supply  of 

>  Contributed  to  Power  by  Walter  B.  Gump. 
172 


TROUBLE   WITH   STEAM   TURBINE   AUXILIARIES 


173 


cooling  water  from  the  same  supply  pipe;  that  is,  the 
pipes,  both  suction  and  discharge,  leading  to  No.  I 
condenser  are  simply  branches  from  No.  2,  which  was 
installed  first  without  consideration  for  a  second  unit. 


TURBINE  AUXILIARIES  AND  PIPING 
FIG.    76 

When  No.  I  was  installed  there  was  a  row  of  columns 
from  the  basement  floor  to  the  main  floor  extending 
in  a  plane  which  came  directly  in  front  of  the  con- 
denser. The  column  P  shown  in  the  plan  was  so  lo- 
cated as  to  prevent  a  direct  connection  between  the 


174  STEAM  TURBINES 

centrifugal  circulating  pump  and  the  condenser 
inlet.  The  centrifugal  pump  was  direct-connected 
to  a  vertical  high-speed  engine,  and  the  coupling  is 
shown  at  E  in  the  elevation. 

Every  possible  plan  was  contemplated  to  accom- 
modate the  engine  and  pump  without  removing  any 
of  the  columns,  and  the  arrangement  shown  was 
finally  adopted,  leaving  the  column  P  in  its  former 
place  by  employing  an  S-connection  from  the  pump 
to  the  condenser.  It  should  be  stated  that  the  pump 
was  purchased  under  a  guarantee  to  deliver  6000  gal- 
lons per  minute  under  a  head  of  50  feet,  with  an  im- 
peller velocity  of  285  revolutions  per  minute.  The 
vertical  engine  to  which  the  pump  was  connected 
proved  to  be  utterly  unfit  for  running  at  a  speed  be- 
yond 225  to  230  revolutions  per  minute,  and  in  addi- 
tion the  S-bend  would  obviously  reduce  the  capacity, 
even  at  the  proper  speed  of  the  impeller. 

Besides  these  factors  there  was  another  feature 
even  more  serious.  It  was  found  that  when  No.  2 
unit  was  operating  No.  i  could  not  get  as  great  a 
quantity  of  circulating  water  as  when  No.  2  was  shut 
down.  This  was  because  No.  2  was  drawing  most 
of  the  water,  and  No.  i  received  only  that  which  No.  2 
could  not  pull  from  the  suction  pipe  A.  This  will 
be  clear  from  the  fact  that  the  suction  and  discharge 
pipes  for  No.  i  were  only  16  inches,  while  those  of 
No  2  were  20  inches  and  16  inches,  respectively.  The 
condenser  for  No.  2  had  1000  square  feet  less  cooling 
surface  than  No.  i,  which  had  6000  square  feet  and 
was  supplied  with  cooling  water  by  means  of  two 


TROUBLE   WITH   STEAM  TURBINE   AUXILIARIES 


175 


centrifugal  pumps  of  smaller  capacity  than  for  No.  i 
and  arranged  in  parallel.  These  were  each  driven  by 
an  electric  motor,  and  were  termed  "The  Siamese 
Twins,"  due  to  the  way  in  which  they  were  con- 
nected. 

The  load  factor  of  the  plant  ranged  from  0.22  to 
0.30,  the  load  being  almost  entirely  lighting,  so  that 
for  the  winter  season  the  load  factor  reached  the 
latter  figure.  The  day  load  was,  therefore,  light  and 
not  sufficient  to  give  one  turbine  more  than  from 
one-fourth  to  one-third  its  rated  capacity.  Under 
these  conditions  No.  i  unit  was  able  to  operate  much 
more  satisfactorily  than  when  fully  loaded,  because 
of  the  fact  that  the  cooling  water  was  more  effective. 
This  was,  of  course,  all  used  by  No.  i  unit  when  No.  2 
was  not  operating.  At  best,  however,  it  was  found 
that  the  vacuum  could  not  be  made  to  exceed  24 
inches,  and  during  the  peak,  with  the  two  turbines 
running,  the  .vacuum  would  often  drop  to  12  inches. 
A  vacuum  of  16  inches  or  18  inches  on  the  peak  was 
considered  good. 

AN  INVESTIGATION 

Severe  criticism  "rained"  heavily  upon  the  engi- 
neer in  charge,  and  complaints  were  made  in  reference 
to  the  high  oil  consumption.  An  investigation  on 
the  company's  part  followed,  and  the  firm  which 
furnished  the  centrifugal  pump  and  engine  was  next 
in  order  to  receive  complaints.  Repeated  efforts  were 
made  to  increase  the  speed  of  the  vertical  engine  to 
285  revolutions  per  minute,  but  such  a  speed  proved 


176  STEAM  TURBINES 

detrimental  to  the  engine,  and  a  lower  speed  of  about 
225  revolutions  per  minute  had  to  be  adopted. 

A  thorough  test  on  the  pump  to  ascertain  its  deliv- 
ery at  various  speeds  was  the  next  move,  and  a  notched 
weir,  such  as  is  shown  in  the  elevation,  was  employed, 
The  test  was  made  on  No.  2  cooling  tower,  not  shown 
in  the  sketch,  and  showed  that  barely  3000  gallons 
per  minute  were  being  delivered  to  the  cooling  tower. 
While  the  firm  furnishing  the  pump  was  willing  to 
concede  that  the  pump  might  not  be  doing  all  it  should, 
attention  was  called  to  the  fact  that  there  might  be 
some  other  conditions  in  connection  with  the  system 
which  were  responsible  for  the  losses.  Notable 
among  these  was  the  hydraulic  friction,  and  when  this 
feature  of  the  case  was  presented,  the  company  did 
not  seem  at  all  anxious  to  investigate  the  matter  fur- 
ther; obviously  on  account  of  facing  a  possible  neces- 
sity for  new  piping  or  other  apparatus  which  might 
cost  something. 

Approximately  34  feet  was  the  static  head  of  water 
to  be  pumped  over  No.  2  cooling  tower.  Pressure 
gages  were  connected  to  the  suction,  discharge,  and 
condenser  inlet,  as  shown  at  G,  G'  and  G"  respectively. 
When  No  i  unit  was  operating  alone  the  gage  G 
showed  practically  zero,  indicating  no  vacuum  in 
the  suction  pipe.  Observing  the  same  gage  when 
No.  2  unit  was  running,  a  vacuum  as  high  as  2  pounds 
was  indicated,  showing  that  No.  2  was  drawing  more 
than  its  share  of  cooling  water  from  the  main  A  and 
hence  the  circulating  pump  for  No.  i  was  fighting  for 
all  it  received.  Gage  G  indicated  a  pressure  of  21 


TROUBLE  WITH  STEAM  TURBINE  AUXILIARIES      177 

pounds,  while  G"  indicated  18.5  pounds,  showing  a 
difference  of  2.5  pounds  pressure  lost  in  the  S-bend. 
This  is  equivalent  to  a  loss  of  head  of  nearly  6  feet, 
0.43  pound  per  foot  head  being  the  constant  employed. 
The  total  head  against  which  the  pump  worked  was 
therefore 

G  +  G  =  21  +  2, 
or 


feet  approximately.     Since   the  static   head  was  34 
feet,  the  head  lost  in  friction  was  evidently 

53  —  34=  19 
feet,  or 


per  cent.,  approximately. 

SUPPLY  OF  COOLING  WATER  LIMITED 

In  addition  to  this  the  supply  of  cooling  water  was 
limited,  the  vacuum  being  extremely  low  at  just  the 
time  when  efficient  operation  should  be  had.  The 
natural  result  occurred,  which  was  this:  As  the  load 
on  the  turbine  increased,  the  amount  of  steam  issuing 
into  the  condenser  increased,  beating  the  circulating 
water  to  a  temperature  which  the  cooling  tower  (not 
in  the  best  condition)  was  unable  to  decrease  to  any 
great  extent.  The  vacuum  gradually  dropped  off, 
which  indicated  that  the  condenser  was  being  filled 
with  vapor,  and  in  a  short  time  the  small  centrifugal 


178  STEAM  TURBINES 

tail-pump  lost  its  prime,  becoming  "vapor  bound," 
and  the  vacuum  further  decreased.  The  steam  which 
had  condensed  would  not  go  into  the  tail-pump 
because  of  the  tendency  of  the  dry-pump  to  maintain 
a  vacuum.  When  a  certain  point  was  reached  the 
dry-vacuum  pump  started  to  draw  water  in  its  cylin- 
der, and  the  unit  had  to  be  shut  down  immediately. 

VAPOR-BOUND  PUMPS 

As  the  circulating  water  gradually  rose  in  tempera- 
ture the  circulating  pump  also  became  "vapor  bound," 
so  that  the  unit  would  be  tied  up  for  the  rest  of  the 
night,  as  this  pump  could  not  be  made  to  draw  hot 
water.  The  reason  for  this  condition  may  be  ex- 
plained in  the  following  way.  When  the  circulating 
pump  was  operating  and  there  was  a  suction  of  2 
pounds  indicated  at  G,  the  water  was  not  flowing  to 
the  pump  of  its  own  accord,  but  was  being  pulled 
through  by  force.  This  water  would  flow  through 
the  pump  until  a  point  was  reached  when  the  water 
became  hot  enough  to  be  converted  into  vapor,  this 
occurring  at  a  point  where  the  pressure  was  sufficiently 
reduced  to  cause  the  water  to  boil.  Naturally  this 
point  was  in  the  suction  pipe  and  vapor  was  thus 
maintained  behind  the  pump  as  long  as  it  was  operat- 
ing. In  this  case  the  pump  was  merely  maintaining 
a  partial  vacuum,  but  not  drawing  water.  After  the 
vacuum  was  once  lost,  by  reason  of  the  facts  given, 
it  could  not  be  regained,  as  the  circulating  water, 
piping  and  condenser  required  a  considerable  period 
of  time  in  which  to  cool. 


TROUBLE  WITH  STEAM  TURBINE  AUXILIARIES      179 

Before  any  radical  changes  were  made  it  was  de- 
cided that  a  man  should  crawl  in  the  suction  pipe  A, 
and  remove  such  sand,  dirt,  or  any  other  obstacles 
as  were  believed  to  cause  the  friction.  After  this 
had  been  done  and  considerable  sand  had  been  re- 
moved, tests  were  resumed  with  practically  the  same 
results  as  before.  The  investigation  was  continued 
and  the  dry-vacuum  pumps  were  overhauled,  as  they 
had  been  damaged  by  water  in  the  cylinders,  and 
furthermore  needed  re-boring.  In  short,  the  auxil- 
iaries were  restored  to  the  best  condition  that  could 
be  brought  about  by  the  individual  improvement 
of  each  piece  of  apparatus.  As  this  was  not  the  seat 
of  the  trouble,  however,  the  remedy  failed  to  effect 
a  "cure."  It  was  demonstrated  that  the  steam  con- 
sumption of  the  turbines  was  greatly  increased  due 
to  priming  of  the  boilers,  as  well  as  condensation  in 
the  turbine  casing;  hence,  the  ills  above  mentioned 
were  aggravated. 

CHANGES  IN  PIPING 

After  a  great  deal  of  argument  from  the  chief  engi- 
neer, and  the  firm  which  furnished  the  pump,  both 
making  a  strong  plea  for  a  change  in  the  piping,  the 
company  accepted  the  inevitable,  and  the  dotted 
portion  shows  the  present  layout.  The  elbow  M  was 
removed,  and  a  tee  put  in  its  place  to  which  the 
piping  D  was  connected.  The  circulating  pump  was 
removed  to  the  position  shown,  and  a  direct  connec- 
tion substituted  for  the  S-bend.  The  discharge  pipe 
C  was  carried  from  No.  i  unit  separately,  as  shown 


l8o  STEAM  TURBINES 

in  the  elevation,  and  terminated  at  No.  i  cooling  tower 
instead  of  No.  2,  which  shortened  the  distance  about 
60  feet,  the  total  length  of  pipe  (one  way)  from  No.  i 
unit  being  originally  250  feet.  In  this  way  the  con- 
densing equipment  was  made  practically  separate  for 
each  turbine,  as  it  should  have  been  in  the  first  place. 

With  the  new  piping  a  vacuum  of  24  inches  on  the 
peak  could  be  reached.  While  this  is  far  from  an  effi- 
cient value,  yet  it  is  better  than  the  former  figure. 
The  failure  to  reach  a  vacuum  of  28  inches  or  better 
is  due  primarily  to  a  lack  of  cooling  water,  but  an 
improvement  in  this  regard  could  be  made  by  recon- 
structing the  cooling  towers,  which  at  present  do 
not  offer  the  proper  amount  of  cooling  surface.  The 
screens  used  were  heavy  galvanized  wire  of  about  W- 
inch  mesh,  which  became  coated  in  a  short  time,  and 
must  be  thoroughly  cleaned  to  permit  the  water  to 
drop  through  them.  The  supply  of  cooling  water 
was  taken  from  a  3O-inch  pipe  line  several  miles  long 
and  fed  from  a  spring.  The  amount  of  water  varied 
considerably  and  was  at  times  quite  insufficient  for 
the  load  on  the  plant.  Instead  of  meeting  this  con- 
dition with  the  best  apparatus  possible,  a  chain  of 
difficulties  were  added  to  it,  with  the  results  given. 


INDEX 

PAGE 

Acceleration,  rate  of  147 

Adjustment,  axial 65 

making 66 

Air-pump,  examining  163 

Allis-Chalmers  Co.  steam  turbine  41 

Auxiliaries a,  154 

special  165 

Auxiliary  plant  for  consumption  test  137 

spring  on  governor  dome 28 

Axial  adjustment 65 

Baffler    36 

functions  39 

Bearings,  main 69 

Blades,  construction  details 44 

inspecting  104 

Blading,  Allis-Chalmers  turbine  48 

Westinghouse- Parsons  turbine  59,  92 

Blueprints,  studying  n 

Buckets,  moving 14 

stationary 14 

Bushings  36 

Carbon  packing 19 

ring 20 

Central  gravity  oiling  system     m 

Circulating  pump  fails  to  meet  guarantee     172 

Clearance 15, 150 

adjusting 18 

i8z 


l8o  STEAM  TURBINES 

in  the  elevation,  and  terminated  at  No.  i  cooling  tower 
instead  of  No.  2,  which  shortened  the  distance  about 
60  feet,  the  total  length  of  pipe  (one  way)  from  No.  i 
unit  being  originally  250  feet.  In  this  way  the  con- 
densing equipment  was  made  practically  separate  for 
each  turbine,  as  it  should  have  been  in  the  first  place. 

With  the  new  piping  a  vacuum  of  24  inches  on  the 
peak  could  be  reached.  While  this  is  far  from  an  effi- 
cient value,  yet  it  is  better  than  the  former  figure. 
The  failure  to  reach  a  vacuum  of  28  inches  or  better 
is  due  primarily  to  a  lack  of  cooling  water,  but  an 
improvement  in  this  regard  could  be  made  by  recon- 
structing the  cooling  towers,  which  at  present  do 
not  offer  the  proper  amount  of  cooling  surface.  The 
screens  used  were  heavy  galvanized  wire  of  about  TV 
inch  mesh,  which  became  coated  in  a  short  time,  and 
must  be  thoroughly  cleaned  to  permit  the  water  to 
drop  through  them.  The  supply  of  cooling  water 
was  taken  from  a  3O-inch  pipe  line  several  miles  long 
and  fed  from  a  spring.  The  amount  of  water  varied 
considerably  and  was  at  times  quite  insufficient  for 
the  load  on  the  plant.  Instead  of  meeting  this  con- 
dition with  the  best  apparatus  possible,  a  chain  of 
difficulties  were  added  to  it,  with  the  results  given. 


INDEX 

PAGE 

Acceleration,  rate  of  147 

Adjustment,  axial 65 

making 66 

Air-pump,  examining  163 

Allis-Chalmers  Co.  steam  turbine  41 

Auxiliaries 2,  154 

special  165 

Auxiliary  plant  for  consumption  test  137 

spring  on  governor  dome 28 

Axial  adjustment 65 

Baffler    36 

functions  39 

Bearings,  main 69 

Blades,  construction  details 44 

inspecting  104 

Blading,  Allis-Chalmers  turbine  48 

Westinghouse- Parsons  turbine  59,  92 

Blueprints,  studying  1 1 

Buckets,  moving 14 

stationary 14 

Bushings  36 

Carbon  packing 19 

ring 20 

Central  gravity  oiling  system     in 

Circulating  pump  fails  to  meet  guarantee     172 

Clearance 15, 150 

adjusting 18 

181 


1 82  INDEX 

PAGE 

between  moving  and  stationary  buckets    4 

gages    17 

measuring   x8 

radial 63 

Comma  lashing    95 

Condensers   108,  131 

jet 154 

Conditions  for  successful  operation    105 

Cooling  water  supply  limited 177 

Coupling    127 

Cover-plate 4 

-plate,  lowering 9 

Curtis  turbine     1 1 

turbine  in  practice i 

setting  valves    3r>32 

De  Laval  turbines 118 

Draining  system     105 

Dummy  leakage 115 

pistons 63,  65 

rings 43,  113,  "4 

Equalizing  pipes 64 

Exhaust  end  of  turbine 107 

Pipe      107 

Expanding  nozzles    14 

Feed-pipes 164 

Flow,  rate 38 

Foundation  drawings 2 

rings 44,  46 

Fourth-stage  wheel    14 

Franklin,  Thomas 112,  137,  154 

Gages,  calibrating  and  adjusting    160 

clearance 17 


INDEX  183 

PAGE 

for  test  work    165 

Generator   53 

Glands,  examination  for  scale 104 

Packing   71,  77 

regulation    148 

Governor,  Allis-Chalmers  turbine     48 

Curtis  turbine     27, 3 1 

improved,  Westinghouse-Parsons  turbine    83 

-rods,  adjusting    35 

safety-stop 86 

Westinghouse-Parsons  turbine     80 

Grinding   38 

Guide-bearing,  lower 9 

Gump,  Walter  B 172 

Holly  draining  system 106 

Horseshoe  shim    8 

Hot-well  regulation   148 

Inspection 103 

Intermediate   14 

Jacking  ring 8 

Jet  condenser 154 

Johnson,  Fred  L 1,31 

Leakage 1 18 

Load  variation 144 

Lower  guide-bearing 9 

Lubrication 51 

Measuring  tanks    171 

Mechanical  valve-gear 32 

Nozzles,  expanding   14 


184  INDEX 

PAGE 

°il  57i  103, 109 

amount  passing  through  bearings  ...  122 

consumption,  high 175 

detecting  water  in  122 

pressure  122 

-temperature  curve 1 23 

Oil,  testing  no 

velocity  of  flow 122 

Oiling 87 

system,  importance : .  119 

Operation,  Allis-Chalmers  turbine  54,  55 

successful 105 

Operations  in  handling  turbine  plant 146 

Overload  valve 28 

Packing,  carbon 19 

glands 71 

ring,  self-centering 14 

Parsons  type  of  turbine ! 41 

Passage  in  foundation 2 

Peep-holes 1 5,  18 

Piping    171 

changing    179 

inspection    164 

Pressure    63 

gages    166 

in  glands 57 

Pump,  circulating,  fails  to  meet  guarantee 172 

inspection    164 

Radial  clearance 63 

Rateau  turbines 118 

Relief  valves  31 

valves,  importance 159 

Ring,  carbon 20 

Rotor,  Westinghouse- Parsons  turbine 59 

Running 99 


INDEX  185 

PAGE 

Safety-stop 22 

-stop  governor 86 

Saucer  steps   1 39 

Screw,  step-bearing 18 

step-supporting    4 

Separators 105 

Setting  spindle  and  cylinder  for  minimum  leakage 115 

valves  in  Curtis  turbine    31, 32 

Shaft,  holding  up  while  removing  support   8 

Shield-plate 26,  36 

Shim,  horseshoe 8 

Shroud  rings 44,  46 

Shrouding  on  buckets  and  intermediates 18 

Shutting  down    101 

Special  turbine  features    127 

Spindle,  lifting    96 

removing 104 

Spraying  mechanism 158 

Stage  valves    28,  31 

Starting  up   54,  95 

Step-bearing,  lowering  to  examine   8 

-bearing  screw    18 

-blocks ." 4 

-lubricant 4 

-pressure    38 

-supporting  screw 4 

-water,  now    38 

Stopping  turbine    56 

Sub-base   8 

Superheated  steam 105 

Test  loads 141 

necessary  features  163 

Testing  oil no 

preparing  turbine  for 145 

steam  turbine 112, 137,  152 


i86  INDEX 

PAGE 

Thermometer,  calibrating  and  testing   169 

oil 1 25 

Thrust-block     1 18 

Top  block   4 

Troubles  with  steam  turbine  auxiliaries    172 

Turbine  features,  special    127 

Vacuum 152 

raising  107 

test 135 

Valve-gear 83 

-gear,  mechanical  22,  3 2 

operation  during  consumption  test 138 

overload  28 

relief  31 

importance  159 

setting  in  Curtis  turbine 31,32 

stage  28,  31 

Vapor  bound  pumps 178 

Water,  cooling,  limited 177 

in  oil,  detecting    122 

-measurement  readings   148 

pressure  1 01 

service    1 26 

importance    119 

tests  of  condenser 133 

used  in  glands    57,  76 

Westinghouse- Parsons  steam  turbine    58 

Wheels 14 

lower  or  fourth-stage     14 

position    18 


Of 


THE  LIBRARY 

TY  OF  CALIFORNIA 


bgineerug 
Library 

TJ 
735 

a  ? 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


A     000316643     6 


STACK 

JBL72 


